Programmer 7500/MAX_PROGRAMMERS.iso/INFO/TURBOPAS/PLOTLIB.ZIP/PLOTLIB.PAS

Pascal/Delphi Source File | 1988-02-18 | 48.7 KB | 1,334 lines

unit plotlib;

{                  Written by Bob Harbour / CP Systems

  This is a library of routines to drive a Tektronix 4662 flatbed plotter.
  It is written in Turbo Pascal V4.0. You can use it for yourself but if
  you plan to sell it or otherwise include it in something for sale please
  contact me. All of the plotter relevant information was obtained from the
  Tektronix manual.
  The data is passed around in a record ( type datablock ) to organize it.
  The record contains the following fields :

         xdata, ydata : datarray;             data point storage area
         npoints : integer;                   number of points in array
         Xmin, Xmax, Ymin, Ymax : real;       limits of data in array
         Xscale, Yscale : real;               plot scaling parameters

     datarray = array [ 1..1000 ] of real;

  The xdata, ydata and npoints fields must be filled in but the routine
  limits will fill in the min and max fields and scalecalc will fill in
  the scale fields. All of these fields must be filled in prior to calling
  either of the plot routines lineplot or dashplot.
  There are routines here to generate linear plots, semi-logarithmic plots
  and log-log plots. These are ready to call complete with labeling.
  The primatives are available so that special plotting requirements can
  be accomodated easily. There are routines for titling in several formats.
  The 4662 plotter requires data in an integer format which are Absolute.
  The plotting routines scale the real data to the absolute format required
  by the plotter. The plotter accepts data as ascii characters so the
  integer data must be converted by vectorgen to an ascii string.
  Below is a list of the externally available routines and a short description
  of what they do.
  The plotter is connected to serial port COM2. }




interface

{----------------------------------------------------------------------------}

uses crt;
{$M 32768,0,655360}                         { increase stack size }

type vecstring = string [5];
     linestring = string [ 40 ];
     datarray = array [ 1..1000 ] of real;

     datablock = record
         xdata, ydata : datarray;            { data point storage area }
         npoints : integer;                  { number of points in array }
         Xmin, Xmax, Ymin, Ymax : real;      { limits of data in array }
         Xscale, Yscale : real;              { plotting parameters }
     end;


var aux : text;

{ ==========  procedures and functions in unit ============================}

procedure vectorgen ( x, y :integer; var outstring : vecstring );
{ generate a vector string from input parameters x and y }

procedure wait ( x,y : integer );
{ calculate length of vector and wait proper amount of time to prevent plotter
  buffer overrun. Assumes full sized plotter area, can be sped up if plotting
  is always done on smaller paper by changing the global constants actualX , Y
  to the smaller paper size }


procedure moveto ( x, y : integer );
{ move pen to position x,y }

procedure drawto ( x, y : integer );
{ draw line to position x,y. note that this routine will repeat unneeded
  bytes if used repetitivly for graphing, filling up the plotter buffer }


procedure writechar ( x, y, theta : integer; charstr : linestring );
{ writes alpha characters starting at position x, y and at angle theta, with
  x and y in plotter address integers and theta in degrees }

procedure deswrite ( x,y : integer; charstr : linestring );
{ writes a descending vertical string starting at x,y in absolute plotter
  coordinates }

procedure vtitle ( x : integer; charstr : linestring );
{ writes title in a descending vertical strip starting at x with x in
  absolute plotter coordinates, Y is chosen by routine to center the title }

procedure htitle ( y : integer; charstr : linestring );
{ prints a horizontal title centered in X on plot at vertical pos Y in
  absolute plotter coordinates }


procedure limits ( var plotdata : datablock );
{ finds the minimum and maximum values for X and Y in the databblock
  and inserts them in the appropriate fields }

procedure scalecalc ( square :boolean; var plotdata : datablock );
{ calculates the scale factor from the min and max values in the block
  if square, the x and y scale factors will be equal and set to the
  smaller of the two. Must be called after mins and maxes are determined }

procedure edlimits ( var plotdata : datablock );
{ shows user the values in min and max for both axes and allows them to be
  changed. Note that the max values cannot be made less than the ones in the
  data block when called and the min values cannot be made greater so it is
  important to call limits before calling this routine. }

procedure showlimits ( var plotdata : datablock );
{ shows values in limit fields and scale fields. mostly for debugging }

procedure lineplot ( var plotdata : datablock );
{ plots solid line through all points in data array }

procedure dashplot ( var plotdata : datablock );
{ plots dashed line through all points in data array, drawing the vectors
  from originating from odd number points and leaving open the vectors
  originating from even number points. Even and odd refering to the array
  indices }


procedure lineargrid ( var plotdata : datablock );
{ prints a grid of linear divisions on plot. must be called after limits
  and scalecalc in order to have the correct values for the line positioning }

procedure linearaxes ( var plotdata : datablock );
{ draws the axes into the graph at the zero lines if they are in the range
  plotted else puts the axes at the edges of the plot. requires the min and
  max and scale data in the incoming block to operate }

procedure lincal ( var plotdata : datablock );
{ writes the mins and maxes in the corners of a linear plot }


procedure semiloggrid ( var griddata : datablock );
{ plots the semi-log axes or grid from the limits in griddata }

procedure semilogcal ( var plotdata : datablock );
{ writes the mins and maxes in the corners of the plot on a semilog plot }


procedure logloggrid ( var griddata : datablock );
{ plots the log-log grid from the limits in griddata }

procedure loglogcal ( var plotdata : datablock );
{ writes the mins and maxes in the corners of the plot on a log-log plot }


procedure linearplot ( var plotstuff : datablock; Hname,Vname : linestring; grid,square : boolean );
{ plots the data in plotstuff on a linear graph. Writes Hname and Vname in the
  appropriate margins and writes the limits in the margins too. If grid, a
  regular graph paper type grid is drawn, else a line at the zeros or closest
  to zero on graph is drawn. If square, scale factors are forced to the minimum
  of X or Y and both are equal. useful for circles or true geometries }

procedure semilogplot ( var plotstuff : datablock; Hname,Vname : linestring );
{ generates a semi-logarithmic plot of the data in plotstuff. Writes string in
  Vname and H name in the margins of the plot. X data is transformed to log
  before plotting }

procedure logplot ( var plotstuff : datablock; Hname,Vname : linestring );
{ generates a log log plot of the data in plotstuff. titles in Hname and Vname
  and data in both axes is transformed to log before plotting }

{--------------------------------------------------------------------------}


implementation

{ control characters and plotter commands and constants }
const esc = #$1B;                           { ascii control characters }
      del = #$7F;
      gs  = #$1D;
      us  = #$1F;
      cr  = #$0D;
      bel = #$07;
      device = 'A';                         { plotter address set in dip sw }
      plotteron = 'E';                      { plotter command characters }
      plotteroff = 'F';
      plotreset = 'N';
      alphareset = 'V';
      alpharotate = 'J';
      comma = ',';

      plotXmax = 4095;                      { extreme right side of plotter }
      plotXmin = 0;                         { extreme left side of plotter }
      plotYmax = 2731;                      { extreme top side of plotter }
      plotYmin = 0;                         { extreme bottom side of pltter }

      axesXmax = 3900;                      { right margin of plot area }
      axesXmin = 600;                       { left margin of plot area }
      axesYmax = 2550;                      { top margin }
      axesYmin = 600;                       { bottom margin }

      lineheight = 88;                      { plotter default line spacing }
      charwidth  = 56;                      { default character width }

      actualX = 10.0;                       { length in inches of plot surface}
      actualY = 8.0;                        { height in inches of plot surface}

{-----------------------------------------------------------------------------}

var  lastX, lastY : integer;
     scaleX, scaleY : real;

{ ============================================================================}


function log ( x : real ) : real;
{ calculates the base 10 logarithm of x }

begin
    log := ln ( x ) / ln ( 10.0 );
end;



function pow ( x : real ) : real;
{ calculates 10 ** x }

begin
     pow := exp ( x * ln ( 10.0));
end;



procedure vectorgen ( x, y :integer; var outstring : vecstring );
{ generate a vector string from input parameters x and y }

const Hioffset = $20;
      LoXoffset = $40;
      LoYoffset = $60;
      XloYoffset = $60;

var   HiX, LoX, vlX, HiY, LoY, vlY, XloY : integer;

begin
      if x > plotXmax then x := plotXmax;      { range check incomming data }
      if x < plotXmin then x := plotXmin;
      if y > plotYmax then y := plotYmax;
      if y < plotYmin then y := plotYmin;

      HiX := x div 128;                 { split off the most significant part }
      LoX := x mod 128;                 { get less significant part }
      vlX := LoX mod 4;                 { get least significant part }
      LoX := LoX div 4;                 { remove least significant part }

      HiY := y div 128;                 { repeat process for Y variable now }
      LoY := y mod 128;
      vlY := LoY mod 4;
      LoY := LoY div 4;

      XloY := vlX + ( 4 * vlY );       { compose extra byte for ls 2 bits x,y }

      outstring := chr ( HiY + Hioffset );    { fill output string now }
      outstring := outstring + chr ( XloY + XloYoffset );
      outstring := outstring + chr ( LoY + LoYoffset );
      outstring := outstring + chr ( HiX + Hioffset );
      outstring := outstring + chr ( LoX + LoXoffset );
end;



procedure wait ( x,y : integer );
{ calculate length of vector and wait proper amount of time to prevent plotter
  buffer overrun. Assumes full sized plotter area, can be sped up if plotting
  is always done on smaller paper by changing the global constants actualX , Y
  to the smaller paper size }


var Xcomp, Ycomp, delta, time : real;
    wtime : word;

begin                                              { find vector length }
    Xcomp := ( lastX - x ) * scaleX;               { get X component }
    Ycomp := ( lastY - y ) * scaleY;
    delta := sqrt ( sqr ( Xcomp ) + sqr ( Ycomp )); { python theorem }

    lastX := x;                                    { swap new end to old end }
    lastY := y;                                    { for next vector }

    if delta < 0.05                                { select calculation meth }
    then time := 0.0                               { these constants came from}
    else if delta < 0.3                            { interpolating the curves }
          then time := 166.0 * delta + 25.0        { in the tektronix manual }
          else if delta < 1.0                      { time is in miliseconds }
                then time := 115.0 * delta + 30.0
                else if delta < 2.55
                      then time := 70.0 * delta + 70.0
                      else time := ( delta - 2.55 ) * 61.5 + 240;
    if time > 0.5                                  { see if any time to wait }
    then begin
            wtime := round ( time );
            delay ( wtime );                       { wait for the plotter }
         end;
end;


procedure moveto ( x, y : integer );
{ move pen to position x,y }
var destination : vecstring;

begin
     vectorgen ( x, y, destination );
     write ( aux, gs, destination );
end;



procedure drawto ( x, y : integer );
{ draw line to position x,y. note that this routine will repeat unneeded
  bytes if used repetitivly for graphing, filling up the plotter buffer }

var destination : vecstring;

begin
     vectorgen ( x, y, destination );
     write ( aux, gs, bel, destination );
end;



procedure writechar ( x, y, theta : integer; charstr : linestring );
{ writes alpha characters starting at position x, y and at angle theta, with
  x and y in plotter address integers and theta in degrees }

begin
      moveto ( x, y );                        { move pen to lower left of ch }
      write ( aux, esc, device, alpharotate, theta );      { set angle }
      write ( aux, us, charstr )              { send string to the plotter }
end;




procedure deswrite ( x,y : integer; charstr : linestring );
{ writes a descending vertical string starting at x,y in absolute plotter
  coordinates }

var i, stop : integer;

begin
     moveto ( x, y );
     stop := length ( charstr );                     { findout how many ch }
     write ( aux, esc, device, alpharotate, '0' );   { set to horizontal }
     write ( aux, us );
     for i := 1 to stop do                           { write chars one/line }
       write ( aux, charstr [ i ], cr );
end;



procedure vtitle ( x : integer; charstr : linestring );
{ writes title in a descending vertical strip starting at x with x in
  absolute plotter coordinates, Y is chosen by routine to center the title }

var y, n : integer;

begin
     n := length ( charstr );                        { findout how many ch }
     y:= ( axesYmax + axesYmin  + ( n * lineheight )) div 2;
     deswrite ( x,y, charstr );                      { go print it }
end;



procedure htitle ( y : integer; charstr : linestring );
{ prints a horizontal title centered in X on plot at vertical pos Y in
  absolute plotter coordinates }

var x :integer;

begin
     x := ( axesXmax + axesXmin - ( length ( charstr ) * charwidth )) div 2 ;
     writechar ( x, y, 0, charstr );               { write it }
end;


procedure limits ( var plotdata : datablock );
{ fills in the limits for the data }

const
      maxreal = 1.7E37;
      minreal = - maxreal;

var   i : integer;

begin
  with plotdata do                      { setup to access the data block }
  begin
     Xmax := minreal;                    { init to extreme opposite values }
     Xmin := maxreal;
     Ymax := minreal;
     Ymin := maxreal;

     for i := 1 to npoints do            { scan for largest and smallest }
     begin
           if xdata [ i ] > Xmax
             then Xmax := xdata [ i ];

           if xdata [ i ] < Xmin
             then Xmin := xdata [ i ];

           if ydata [ i ] > Ymax
             then Ymax := ydata [ i ];

           if ydata [ i ] < Ymin
             then Ymin := ydata [ i ];
     end;

   end;
end;


procedure scalecalc ( square :boolean; var plotdata : datablock );
{ calculates the scale factor from the min and max values in the block
  if square, the x and y scale factors will be equal and set to the
  smaller of the two. Must be called after mins and maxes are determined }

var tempX, tempY : real;

begin
     with plotdata do
      begin
        tempX := axesXmax - axesXmin;
        tempY := axesYmax - axesYmin;
                 { calculate scaling factors }
        xscale := tempX / ( Xmax - Xmin ) ;
        yscale := tempY / ( Ymax - Ymin ) ;

        if square                          { if square, make scale factors = }
        then begin if xscale < yscale
                     then yscale := xscale;
                   if yscale < xscale
                     then xscale := yscale;
             end;
      end;
end;



function getnum ( numstr : linestring ) : real;
{ checks string for non numeric characters and converts the remaining string
  to a real number. }

var i, strlength, code : integer;
    temp : real;
    tempstr : linestring;
begin
     repeat
       i := 1;                            { set up to find first number }
       strlength := length ( numstr );
       while not ( numstr [ i ] in [ '+','-','0'..'9' ] ) and (i <= strlength) do
        i := i + 1;                       { find first numeric }

       if i <= strlength
       then begin
             tempstr := copy ( numstr ,i ,strlength );
             val ( tempstr, temp, code );{ convert it }
             if code <> 0
              then begin write ( 'Please re-enter new value : ');
                         readln ( numstr );
                   end;
            end

       else begin write ( 'Please re-enter new value : ');
                  readln ( numstr );
                  code := 1;                         { set dummy value }
            end;

     until code = 0;

     getnum := temp;                                 { assign function value}
end;


procedure edlimits ( var plotdata : datablock );
{ displays mins and maxes and allows the user to edit them }

var instring : linestring;
    command : string [ 4 ];
    temp : real;

begin
   with plotdata do
          repeat                                  { until instring ='' }

             writeln ('Xmax = ',Xmax,'     Ymax = ',Ymax );
             writeln ('Xmin = ',Xmin,'     Ymin = ',Ymin );
             writeln;
             write ('Enter : parameter new_value     or return to continue : ');
             readln ( instring );

             if instring <> ''                    { is there a string there ?}
             then
               begin
                 command := copy ( instring, 1, 4 );

                 if (command = 'ymin') or (command = 'Ymin')
                  then begin
                         temp := getnum ( instring );
                         if temp <= Ymin                  { is change legal? }
                           then Ymin := temp              { yes, do it }
                           else writeln ('New value too large!');
                       end

                  else if (command = 'ymax') or (command = 'Ymax')
                        then begin
                              temp := getnum ( instring );
                              if temp >= Ymax              { is change legal? }
                                then Ymax := temp          { yes, do it }
                                else writeln ('New value too small!');
                             end


                        else if (command = 'xmin') or (command = 'Xmin')
                              then begin
                                     temp := getnum ( instring );
                                     if temp <= Xmin       { is change legal? }
                                       then Xmin := temp   { yes, do it }
                                       else writeln ('New value too large!');
                                   end


                              else if (command = 'xmax') or (command = 'Xmax')
                                    then begin
                                           temp := getnum ( instring );
                                           if temp >= Xmax
                                             then Xmax := temp
                                             else writeln ('New value too small!');
                                         end

                                    else writeln ('Invalid parameter name ');
               end;
          until instring = '';

end;





procedure showlimits ( var plotdata : datablock );
{ displays the contents of the min and max and scale factors for block
  passed in }

begin with plotdata do
        begin
           writeln ( 'Xmax = ',Xmax,'  Xmin = ',Xmin,'   X scale = ',xscale );
           writeln ( 'Ymax = ',Ymax,'  Ymin = ',Ymin,'   Y scale = ',yscale );
        end;
end;




procedure lineplot ( var plotdata : datablock );
{ plots solid line through all points in data array }

var i, x, y :integer;
    destination : vecstring;
    firstpair : boolean;

begin
     firstpair := true;                 { indicate first pair transmitted }
     with plotdata do                   { get access to data and limits }
       begin
            for i := 1 to npoints do    { do whole array of points }
            begin
                     { calculate plotter coords from data }
              x := round (( xdata [ i ] - Xmin ) * xscale ) + axesXmin;
              y := round (( ydata [ i ] - Ymin ) * yscale ) + axesYmin;
              vectorgen ( x, y, destination );      { generate output string }

              if firstpair                          { see if first point sent }
                then begin                          { yes, send whole command }
                       write ( aux, gs, destination );
                       firstpair := false;          { reset flag }
                     end
                else
                     write ( aux, destination );

              wait ( x,y );                         { wait for plotter to draw}

            end;
       end;
end;


procedure dashplot ( var plotdata : datablock );
{ plots dashed line through all points in data array, drawing the vectors
  from originating from odd number points and leaving open the vectors
  originating from even number points. Even and odd refering to the array
  indices }

var i, x, y :integer;
    destination : vecstring;
    odd : boolean;

begin
     odd := true;                       { indicate odd pair to transmit }
     with plotdata do                   { get access to data and limits }
       begin
            for i := 1 to npoints do    { do whole array of points }
            begin
                     { calculate plotter coords from data }
              x := round (( xdata [ i ] - Xmin ) * xscale ) + axesXmin;
              y := round (( ydata [ i ] - Ymin ) * yscale ) + axesYmin;

              vectorgen ( x, y, destination );      { generate output string }

              if odd                                { see if odd or even  }
                then begin                          { odd, move to it }
                       write ( aux, gs, destination );
                       odd := false;                { toggle flag }
                     end
                else
                     begin                          { even, draw to this one }
                       write ( aux, destination );
                       odd := true;                 { toggle flag }
                     end;

              wait ( x,y );                         { wait for plotter to draw}

            end;
       end;
end;


procedure lineargrid ( var plotdata : datablock );
{ prints a grid of linear divisions on plot. must be called after limits
  and scalecalc in order to have the correct values for the line positioning }

const Hlines = 11;                             { number of horizontal lines }
      Vlines = 11;
var griddata : datablock;
    Xrange, Yrange, Xincrement, Yincrement, X, Y : real;
    i, firstY, lastY :integer;
    odd : boolean;

begin
     with plotdata do
     begin
         griddata.Xmax := Xmax;               { copy this data over }
         griddata.Xmin := Xmin;
         griddata.Xscale := Xscale;
         griddata.Ymax := Ymax;
         griddata.Ymin := Ymin;
         griddata.Yscale := Yscale;

         Xrange := Xmax - Xmin;               { Get stuff out of this block }
         Yrange := Ymax - Ymin;
     end;

     Xincrement := Xrange / ( Vlines - 1 );  { determine the spacing of lines }
     Yincrement := Yrange / ( Hlines - 1 );

     with griddata do                        { start filling the grid data }
     begin
       X := Xmin;                            { init the counters }
       Y := Ymin;
       odd := true;                          { init the flag }

       for i := 1 to ( Hlines  * 2 ) do      { generate the horizontal lines }
       begin
           if odd
           then begin                        { begin a written vector }
                  xdata [ i ] := Xmin;       { put data into the data block }
                  ydata [ i ] := Y;
                  odd := false;              { toggle flag }
                end
           else begin                        { start an unwritten vector }
                  xdata [ i ] := Xmax;
                  ydata [ i ] := Y;
                  Y:= Y + Yincrement;        { advance to next line up }
                  odd := true;               { toggle flag }
                end;
      end;                                   { horizontal lines are done }

      firstY := ( hlines * 2 ) + 1;          { first vertical line beginning }
      lastY := ( hlines * 2 ) + 1 + ( vlines *2 );  { last point for vert }

      for i := firstY to lastY do            { generate vertical lines now }
      if odd
        then begin                           { generate a written vector }
                 xdata [ i ] := X;
                 ydata [ i ] := Ymin;
                 odd := false;               { toggle flag }
             end
        else begin                           { generate an unwritten vector }
                 xdata [ i ] := X;
                 ydata [ i ] := Ymax;
                 X := X + Xincrement;        { set up for next line }
                 odd := true;                { toggle flag }
             end;
                                             { last of vertical lines }

      npoints := lastY;                      { tell it how many points }
     end;                                    { with griddata }
     dashplot ( griddata );                  { draw the lines }
end;



procedure linearaxes ( var plotdata : datablock );
{ draws the axes into the graph at the zero lines if they are in the range
  plotted else puts the axes at the edges of the plot. requires the min and
  max and scale data in the incoming block to operate }

const ticsize = 0.01;                         { size of scale tick marks }
      numXtics = 10;
      numYtics = 10;

var axesdata : datablock;
    i : integer;
    ticdev, x, y, xincrement, yincrement, xrun, yrun : real;

begin
   with plotdata do
     begin
         axesdata.Xmin := Xmin;              { copy required parameters }
         axesdata.Xmax := Xmax;
         axesdata.Ymin := Ymin;
         axesdata.Ymax := Ymax;
         axesdata.Xscale := Xscale;
         axesdata.Yscale := Yscale;
     end;

   with axesdata do
     begin                                    { find where to put axes }
         if ( Ymax * Ymin ) < 0.0             { is Ymin < 0 < Ymax ? }
           then y := 0.0                      { yes, put axis on it }
           else if Ymin >= 0.0                { no, is graph above the X axis }
                 then y := Ymin               { yes, put axis at the bottom }
                 else y := Ymax;              { no, put axis at the top }

         if ( Xmax * Xmin ) < 0.0             { is Xmin < 0 < Xmax ? }
           then x := 0.0                      { yes, put axis on it }
           else if Xmin >= 0.0                { no, is graph right of Y axis }
                 then x := Xmin               { yes, put axis on left side }
                 else x := Xmax;              { no, put axis at the left }


         xincrement := ( Xmax - Xmin ) / numXtics;  { calculate spacing }
         yincrement := ( Ymax - Ymin ) / numYtics;

         xrun := x;                             { initialize running variable }
         yrun := y;

         while ( xrun - xincrement ) > Xmin do  { back up close to edge }
            xrun := xrun - xincrement;

         while ( yrun - yincrement ) > Ymin do
            yrun := yrun - yincrement;

                                                { set up to put X axis in }
         ticdev := ( Ymax - Ymin ) * ticsize;   { scale the tics to the graph }

         npoints := 1;                          { init counter / index }
         xdata [ npoints ] := Xmin;             { start at left edge }
         Ydata [ npoints ] := y;

         while xrun <= Xmax do
         begin                                  { cross whole graph }
           npoints := npoints + 1;
           xdata [ npoints ] := xrun;
           ydata [ npoints ] := y;

           npoints := npoints + 1;              { place top half of tic }
           xdata [ npoints ] := xrun;
           ydata [ npoints ] := y + ticdev;

           npoints := npoints + 1;              { place bottom half of tic }
           xdata [ npoints ] := xrun;
           ydata [ npoints ] := y - ticdev;

           npoints := npoints + 1;              { move back to the axis }
           xdata [ npoints ] := xrun;
           ydata [ npoints ] := y;

           xrun := xrun + xincrement;           { advance to next tic }
         end;

         npoints := npoints +1;
         xdata [ npoints ] := Xmax;             { make sure axis goes to edge }
         ydata [ npoints ] := y;

     end;                                       { with axesdata }

     lineplot ( axesdata );                     { draw x axis }

     with axesdata do
       begin
       npoints := 1;                            { init counter / index }
       ticdev := ( Xmax - Xmin ) * ticsize;

       xdata [ npoints ] := x;                  { start at bottom edge }
       ydata [ npoints ] := Ymin;

         while yrun <= Ymax do
         begin                                  { cross whole graph }
           npoints := npoints + 1;
           xdata [ npoints ] := x;
           ydata [ npoints ] := yrun;

           npoints := npoints + 1;              { place right half of tic }
           xdata [ npoints ] := x + ticdev;
           ydata [ npoints ] := yrun;

           npoints := npoints + 1;              { place left half of tic }
           xdata [ npoints ] := x - ticdev;
           ydata [ npoints ] := yrun;

           npoints := npoints + 1;              { move back to the axis }
           xdata [ npoints ] := x;
           ydata [ npoints ] := yrun;

           yrun := yrun + yincrement;           { advance to next tic }
         end;

         npoints := npoints + 1;                { make sure axis goes to edge }
         xdata [ npoints ] := x;
         ydata [ npoints ] := Ymax;

     end;                                       { with axesdata }

     lineplot ( axesdata );                     { draw y axis }
end;








procedure lincal ( var plotdata : datablock );
{ writes the mins and maxes in the corners of a linear plot }

var x,y,n : integer;
    outstring : linestring;

begin
    with plotdata do
    begin
        str ( Ymax:5, outstring );                { get string version of 1st }
        n := length ( outstring );                { how many chars }
        x := axesXmin - ( n + 1 ) * charwidth;    { calc where to print it }
        y := axesYmax - lineheight div 2;
        writechar ( x,y,0,outstring );            { write it }

        str ( Ymin:5, outstring );                { get string version of 2nd }
        n := length ( outstring );                { how many chars }
        x := axesXmin - ( n + 1 ) * charwidth;    { calc where to print it }
        y := axesYmin - lineheight div 2;
        writechar ( x,y,0,outstring );            { write it }

        str ( Xmin:5, outstring );                { get string version of 3rd }
        n := length ( outstring );                { how many chars }
        x := axesXmin - (( n * charwidth ) div 2 );  { calc where to put it }
        y := axesYmin - 2 * lineheight;
        writechar ( x,y,0, outstring );           { write it }

        str ( Xmax:4, outstring );                { get string version of 4th }
        n := length ( outstring );                { how many chars }

        x := axesXmax - (( n * charwidth ) div 2 );    { calc where to put it }
        if ( x + ( n + 1 ) * charwidth ) > plotXmax    { make sure it fits }
          then x := plotXmax - ( n + 2 ) * charwidth;  { no, make it fit! }

        y := axesYmin - 2 * lineheight;
        writechar ( x,y,0, outstring );           { write it }
    end;
end;




procedure semiloggrid ( var griddata : datablock );
{ plots the semi-log axes or grid from the limits in griddata }

const hlines = 11;

var hiX,loX, dectemp, decade, units, x, yrange, yincrement, y : real;
    i, n : integer;

begin
  with griddata do
    begin
       i := 1;                                { init index counter }
       hiX := Xmax;
       loX := Xmin;
       decade := loX;

                                    { generate vertical lines first }
       while decade < hiX do                  { generate the decade loop }
       begin
          dectemp := pow ( decade );          { keep this out of the loop }
          units := 1.0;

          while units <= 9.0 do
          begin
              x:= log ( units * dectemp);
              xdata [ i ] := x;
              ydata [ i ] := Ymin;
              i := i + 1;                     { increment index }

              xdata [ i ] := x;
              ydata [ i ] := Ymax;
              i := i + 1;

              units := units + 1.0;          { increment units }
          end;

        decade := decade + 1.0;            { increment power of ten }
       end;

       if x < Xmax                         { is log axis complete ? }
         then begin
                xdata [ i ] := Xmax;       { no, put in last line }
                ydata [ i ] := Ymax;
                i := i + 1;
                xdata [ i ] := Xmax;
                ydata [ i ] := Ymin;
                i := i + 1;
              end;

                                  { now do the horizontal lines }
       yrange := Ymax - Ymin;
       yincrement := Yrange / ( hlines - 1 );   { calculate the spacing }
       y := Ymin;                               { init the running pointer }

       for n := 1 to hlines do
       begin
            xdata [ i ] := Xmax;                { generate line vectors }
            ydata [ i ] := y;
            i := i + 1;                         { increment index counter }

            xdata [ i ] := Xmin;
            ydata [ i ] := y;
            i := i + 1;
            y := y + yincrement;                { set up for next line }
       end;

       npoints := i - 1;                        { save point count in block }

    end;                                        { with }

       dashplot ( griddata );                   { draw the vectors }
end;






procedure semilogcal ( var plotdata : datablock );
{ writes the mins and maxes in the corners of the plot on a semilog plot }

var x,y,n,temp : integer;
    outstring, digstring : linestring;

begin
    with plotdata do
    begin
        str ( Ymax:5, outstring );                { get string version of 1st }
        n := length ( outstring );                { how many chars }
        x := axesXmin - ( n + 1 ) * charwidth;    { calc where to print it }
        y := axesYmax - lineheight div 2;
        writechar ( x,y,0,outstring );            { write it }

        str ( Ymin:5, outstring );                { get string version of 2nd }
        n := length ( outstring );                { how many chars }
        x := axesXmin - ( n + 1 ) * charwidth;    { calc where to print it }
        y := axesYmin - lineheight div 2;
        writechar ( x,y,0,outstring );            { write it }

        outstring := '10 E';                      { start horizontal label }
        temp := round ( Xmin );
        str ( temp, digstring );                  { get string version }
        outstring := outstring + digstring;
        n := length ( outstring );                { how many chars }
        x := axesXmin - (( n * charwidth ) div 2 );  { calc where to put it }
        y := axesYmin - 2 * lineheight;
        writechar ( x,y,0, outstring );           { write it }

        outstring := '10 E';
        temp := round ( Xmax );
        str ( temp, digstring );                  { get string version  }
        outstring := outstring + digstring;
        n := length ( outstring );                { how many chars }

        x := axesXmax - (( n * charwidth ) div 2 );    { calc where to put it }
        if ( x + ( n + 1 ) * charwidth ) > plotXmax    { make sure it fits }
          then x := plotXmax - ( n + 2 ) * charwidth;  { no, make it fit! }

        y := axesYmin - 2 * lineheight;
        writechar ( x,y,0, outstring );           { write it }
    end;
end;



procedure loglogcal ( var plotdata : datablock );
{ writes the mins and maxes in the corners of the plot on a log-log plot }

var x,y,n,temp : integer;
    outstring, digstring : linestring;

begin
    with plotdata do
    begin
        outstring := '10 E';                      { get first part of label }
        temp := round ( Ymax );                   { get value for exponent }
        str (temp, digstring );                   { get string version of exp }
        outstring := outstring + digstring;       { combine them }
        n := length ( outstring );                { how many chars }
        x := axesXmin - ( n + 1 ) * charwidth;    { calc where to print it }
        y := axesYmax - lineheight div 2;
        writechar ( x,y,0,outstring );            { write it }

        outstring := '10 E';                      { get first part of label }
        temp := round ( Ymin );                   { get value for exponent }
        str (temp, digstring );                   { get string version of exp }
        outstring := outstring + digstring;       { combine them }
        n := length ( outstring );                { how many chars }
        x := axesXmin - ( n + 1 ) * charwidth;    { calc where to print it }
        y := axesYmin - lineheight div 2;
        writechar ( x,y,0,outstring );            { write it }

        outstring := '10 E';                      { start horizontal label }
        temp := round ( Xmin );
        str ( temp, digstring );                  { get string version }
        outstring := outstring + digstring;
        n := length ( outstring );                { how many chars }
        x := axesXmin - (( n * charwidth ) div 2 );  { calc where to put it }
        y := axesYmin - 2 * lineheight;
        writechar ( x,y,0, outstring );           { write it }

        outstring := '10 E';
        temp := round ( Xmax );
        str ( temp, digstring );                  { get string version  }
        outstring := outstring + digstring;
        n := length ( outstring );                { how many chars }

        x := axesXmax - (( n * charwidth ) div 2 );    { calc where to put it }
        if ( x + ( n + 1 ) * charwidth ) > plotXmax    { make sure it fits }
          then x := plotXmax - ( n + 2 ) * charwidth;  { no, make it fit! }

        y := axesYmin - 2 * lineheight;
        writechar ( x,y,0, outstring );           { write it }
    end;
end;



procedure logloggrid ( var griddata : datablock );
{ plots the log-log grid from the limits in griddata }

var dectemp, decade, units, x, y : real;
    i, n : integer;

begin
  with griddata do
    begin
       i := 1;                                { init index counter }
       decade := Xmin;

                                    { generate vertical lines first }
       while decade < Xmax do                 { generate the decade loop }
       begin
          dectemp := pow ( decade );          { keep this out of the loop }
          units := 1.0;

          while units <= 9.0 do
          begin
              x:= log ( units * dectemp);
              xdata [ i ] := x;
              ydata [ i ] := Ymin;
              i := i + 1;                     { increment index }

              xdata [ i ] := x;
              ydata [ i ] := Ymax;
              i := i + 1;

              units := units + 1.0;          { increment units }
          end;

        decade := decade + 1.0;            { increment power of ten }
       end;

       if x < Xmax                         { is log axis complete ? }
         then begin
                xdata [ i ] := Xmax;       { no, put in last line }
                ydata [ i ] := Ymax;
                i := i + 1;
                xdata [ i ] := Xmax;
                ydata [ i ] := Ymin;
                i := i + 1;
              end;

                                  { now do the horizontal lines }
       decade := Ymin;

       while decade < Ymax do                 { generate the decade loop }
       begin
          dectemp := pow ( decade );          { keep this out of the loop }
          units := 1.0;

          while units <= 9.0 do
          begin
              y:= log ( units * dectemp);
              xdata [ i ] := Xmin;
              ydata [ i ] := y;
              i := i + 1;                     { increment index }

              xdata [ i ] := Xmax;
              ydata [ i ] := y;
              i := i + 1;

              units := units + 1.0;          { increment units }
          end;

        decade := decade + 1.0;            { increment power of ten }
       end;

       if y < Ymax                         { is log grid complete ? }
         then begin
                xdata [ i ] := Xmax;       { no, put in last line }
                ydata [ i ] := Ymax;
                i := i + 1;
                xdata [ i ] := Xmin;
                ydata [ i ] := Ymax;
                i := i + 1;
              end;


       npoints := i - 1;                        { save point count in block }

    end;                                        { with }

       dashplot ( griddata );                   { draw the vectors }
end;



procedure logplot ( var plotstuff : datablock; Hname,Vname : linestring );
{ generates a log log plot of the data in plotstuff }

var gridstuff : datablock;
    temp : real;
    i : integer;
label exit;
begin
    limits ( plotstuff );                    { find the mins and maxs }

    if plotstuff.Xmin <= 0.0                 { make sure legal for log }
      then begin writeln ('Xmin <= 0, can''t take log for log plot');
                 goto exit;
           end;

    if plotstuff.Ymin <= 0.0                 { make sure legal for log }
      then begin writeln ('Ymin <= 0, can''t take log for log plot');
                 goto exit;
           end;

    edlimits ( plotstuff );                  { allow user chance to change }

    if plotstuff.Xmin <= 0.0                 { make sure legal for log }
      then begin writeln ('Xmin <= 0, can''t take log for log plot');
                 goto exit;
           end;

    if plotstuff.Ymin <= 0.0                 { make sure legal for log }
      then begin writeln ('Ymin <= 0, can''t take log for log plot');
                 goto exit;
           end;

    with plotstuff do
    begin                    { set up mins and maxes so grid comes out right }

      temp := log ( Xmin );
      if temp >= 0.0
      then Xmin := int ( temp )              { get the plotting min for >1 }
      else if frac ( temp ) = 0.0            { or for 0 < Xmin < 1 }
             then Xmin := int ( temp )
             else Xmin := int ( temp ) - 1.0;

      temp := log ( Xmax );
      Xmax := int ( temp );                  { and max }
      if frac ( temp ) > 0.0
         then Xmax := Xmax + 1.0;            { if any decimal part,use whole }

      temp := log ( Ymin );
      if temp >= 0.0
      then Ymin := int ( temp )              { get the plotting min for >1 }
      else if frac ( temp ) = 0.0            { or for 0 < Ymin < 1 }
             then Ymin := int ( temp )
             else Ymin := int ( temp ) - 1.0;

      temp := log ( Ymax );
      Ymax := int ( temp );                  { and max }
      if frac ( temp ) > 0.0
         then Ymax := Ymax + 1.0;            { if any decimal part,use whole }

      gridstuff.Ymax := Ymax;                { copy the Y limits over }
      gridstuff.Ymin := Ymin;
      gridstuff.Xmax := Xmax;                { copy the X limits over }
      gridstuff.Xmin := Xmin;
      writeln('converting data array ');
      for i := 1 to npoints do
       begin
        xdata [ i ] := log ( xdata [ i ] );  { translate linear to log }
        ydata [ i ] := log ( ydata [ i ] );
       end;

      scalecalc ( false, plotstuff );        { figure out the scale factors }
      gridstuff.xscale := xscale;            { copy the scale factors over }
      gridstuff.yscale := yscale;
    end;

    writeln (' generating grid coords ');
    logloggrid ( gridstuff );                { draw the grid }
    lineplot ( plotstuff );                  { plot the transformed data }
    loglogcal ( plotstuff );                 { put the limits on the graph }
    Htitle ( 200,Hname );                    { put names on the axes }
    Vtitle ( 200,Vname );
exit : end;




procedure semilogplot ( var plotstuff : datablock; Hname,Vname : linestring );
{ generates a semi-logarithmic plot of the data in plotstuff }

var gridstuff : datablock;
    temp : real;
    i : integer;

label exit;

begin
    limits ( plotstuff );                    { find the mins and maxs }

    if plotstuff.Xmin <= 0.0                 { make sure legal for log }
      then begin writeln ('Xmin <= 0, can''t take log for semilog plot');
                 goto exit;
           end;

    edlimits ( plotstuff );                  { allow user chance to change }

    if plotstuff.Xmin <= 0.0                 { make sure legal for log }
      then begin writeln ('Xmin <= 0, can''t take log for semilog plot');
                 goto exit;
           end;

    with plotstuff do
    begin

      temp := log ( Xmin );
      if temp >= 0.0
      then Xmin := int ( temp )              { get the plotting min for >0 }
      else if frac ( temp ) = 0.0            { or for negative }
             then Xmin := int ( temp )
             else Xmin := int ( temp ) - 1.0;

      temp := log ( xmax );
      Xmax := int ( temp );                  { and max }
      if frac ( temp ) > 0.0
         then Xmax := Xmax + 1.0;            { if any decimal part,use whole }

      gridstuff.Ymax := Ymax;                { copy the Y limits over }
      gridstuff.Ymin := Ymin;
      gridstuff.Xmax := Xmax;                { copy the X limits over }
      gridstuff.Xmin := Xmin;

      writeln ('converting X data to log ');
      for i := 1 to npoints do
        xdata [ i ] := log ( xdata [ i ] );  { translate linear to log }

      scalecalc ( false, plotstuff );        { figure out the scale factors }
      gridstuff.xscale := xscale;            { copy the scale factors over }
      gridstuff.yscale := yscale;
    end;

    semiloggrid ( gridstuff );               { draw the grid }
    lineplot ( plotstuff );                  { plot the transformed data }
    semilogcal ( plotstuff );                { put the limits on the graph }
    Htitle ( 200,Hname );                    { put names on the axes }
    Vtitle ( 200,Vname );
exit : end;



procedure linearplot ( var plotstuff : datablock; Hname,Vname : linestring; grid,square : boolean );
{ plots the data in plotstuff on a linear graph. Writes Hname and Vname in the
  appropriate margins and writes the limits in the margins too. If grid, a
  regular graph paper type grid is drawn, else a line at the zeros or closest
  to zero on graph is drawn. If square, scale factors are forced to the minimum
  of X or Y and both are equal. useful for circles or true geometries }

begin
    limits ( plotstuff );                    { scan for mins and maxes }
    edlimits ( plotstuff );                  { allow user to change limits }
    scalecalc ( false, plotstuff );          { calculate the scale factors }

    if grid                                  { use grid or axes ? }
      then lineargrid ( plotstuff )
      else linearaxes ( plotstuff );

    lineplot ( plotstuff );                  { plot the data itself }
    lincal ( plotstuff );                    { put values at the axes }
    vtitle ( 200,Vname);                     { put labels on the axes }
    htitle ( 200,Hname);
end;




begin                                       { initialization }
      assign ( aux, 'com1' );               { open the file for plotter i/o }
      rewrite ( aux );
      write ( aux, esc, device, plotteron );

      lastX := plotXmax;                    { init previous position vars }
      lastY := plotYmax;
      scaleX := actualX / ( plotXmax - plotXmin );   { inches / integer }
      scaleY := actualY / ( plotYmax - plotYmin );

end.