Octave can work with gnuplot, Grace, PLplot. Some people deem PLplot is a replacement of the traditional gnuplot in Octave. If a single data argument is supplied, it is taken as the set of Y coordinates and the X coordinates are taken to be the indices of the elements, starting with 1. results in a vector with n linearly spaced numbers between b and l. It is often used to produce the vector X in the two-argument form of plot. Furthermore, a set of property-value pairs may also be applied, simultanously, to each 'line' drawn by plot. Here instead of line plot we place a '+' marker on the graph for each datapoint, choose the first color (red), and add a legend. >,>, help colormap 'colormap' is a function from the file C:OctaveOctave-4.0.1shareoctave4.0.1 mimagecolormap.m If the device is omitted, it is inferred from the file extension, or if there is no filename it is sent to the printer as postscript. Source.