Splot also contains some custom functions specialized for generating scientific plots. These, such as plotdata( );, depart from the postscript model in the sense that they are implicitly stroked. Implicitly stroked functions do not require a stroke(); in order to mark the page. It is possible to override implicit stroking by starting with a newpath( ); command.
There is a function called readdata(); which reads in tabular data from a data file into an array. The data file must be in ASCII format with one line per data point with the x, y and optional error values each in separate columns. This data can then be drawn inside an axes box using plotdata(); if the default tick positions, size and labelling are acceptable. Alternatively, custom axes boxes, tick marks and labels can be generated using the axes_box();, tickmarks();, and ticklabel( ); commands followed by a drawdata(); or plotdata(); to draw the data points found in the data array. The difference between drawdata(); and plotdata(); is that plotdata(); will pick default values for the axes box, tickmarks or ticklabels if not previously explicitly specified. The plotted data uses the current line colour, style and width to connect the data points if an ordinary plot was selected. Alternatively, the current symbol can be drawn at each data point. There is a function which automatically draws error bars as well as one which fits and draws the best straight line to a set of data points. The data points actually plotted are easily restricted to those within a range of x or y values. The data can also easily be shifted and scaled before plotting.