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C/C++ Source or Header  |  1989-04-29  |  902 b   |  36 lines
  1. /* Demonstration of contour plotting */
  2.       
  3. #define NPTS      41
  4.  
  5. float tr[6] = {0.05, 0.0, -1.05, 0.0, 0.05, -1.05};
  6.  
  7. static float clevel[11] = {-1.,-.8,-.6,-.4,-.2,0,.2,.4,.6,.8,1.};
  8.  
  9. static int mark=1500, space=1500;
  10.  
  11. main()
  12. {
  13.       int i, j;
  14.       float xx, yy;
  15.       float z[NPTS][NPTS], w[NPTS][NPTS];
  16.       void xform();
  17.  
  18.       for (i=0; i<NPTS; i++) {
  19.         xx = (double)(i-(NPTS/2))/(double)(NPTS/2);
  20.         for (j=0; j<NPTS; j++)  {
  21.           yy = (double)(j-(NPTS/2))/(double)(NPTS/2) - 1.0;
  22.           z[i][j] = xx*xx - yy*yy;
  23.           w[i][j] = 2*xx*yy;
  24.         }
  25.       }
  26.  
  27.       plstar(1,1);
  28.       plenv(-1.0,1.0,-1.0,1.0,0,0);
  29.       plcont(z,NPTS,NPTS,1,NPTS,1,NPTS,clevel,11,xform);
  30.       plstyl(1,&mark,&space);
  31.       plcont(w,NPTS,NPTS,1,NPTS,1,NPTS,clevel,11,xform);
  32.       pllab("X Coordinate", "Y Coordinate","Contour Plots of Saddle Points");
  33.       pltext();
  34.       plend();
  35. }
  36.