The simplest 2D plot is `plot(x,y)` or `plot(y)`: this is the plot of
`y` as function of `x` where `x` and `y` are 2 vectors; if
`x` is missing, it is replaced by the vector `(1,size(y,'*')))`.
If `y` is a matrix, its rows are plotted. There are optional arguments.

A first example is given by the following commands and one of the results is represented on figure 5.1:

t=(0:0.05:1)'; ct=cos(2*%pi*t); // plot the cosine plot(t,ct); // xset() opens the toggle panel and // some parameters can be changed with mouse clicks // given by commands for the demo here xset("font",5,4);xset("thickness",3); // plot with captions for the axis and a title for the plot // if a caption is empty the argument ' ' is needed plot(t,ct,'Time','Cosine','Simple Plot'); // click on a color of the xset toggle panel and do the previous plot again // to get the title in the chosen color

The generic 2D multiple plot is

`plot2di(x,y,<options>)`

- index of
`plot2d`

:`i=missing,2,3,4`.For the different values of

`i`we have:`i=missing`: piecewise linear/logarithmic plotting`i=2`: piecewise constant drawing style`i=3`: vertical bars`i=4`: arrows style (e.g. ode in a phase space)

t=(1:0.1:8)';xset("font",2,3); subplot(2,2,1) plot2d([t t],[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d-Piecewise linear'); // subplot(2,2,2) plot2d(t,[1.5+0.2*sin(t) 2+cos(t)],logflag='ll'); xtitle('Plot2d1-Logarithmic scales'); // subplot(2,2,3) plot2d2(t,[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d2-Piecewise constant'); // subplot(2,2,4) plot2d3(t,[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d3-Vertical bar plot')

- Parameters
`x,y`: two matrices of the same size`[nl,nc]`(`nc`is the number of curves and`nl`is the number of points of each curve).For a single curve the vector can be row or column:

`plot2d(t',cos(t)') plot2d(t,cos(t))`are equivalent. - option
`style`:it is a real vector of size`(1,nc)`; the style to use for curve j is defined by`size(j)`(when only one curve is drawn`style`can specify the style and a position to use for the caption).xmax=5.;x=0:0.1:xmax; u=[-0.8+sin(x);-0.6+sin(x);-0.4+sin(x);-0.2+sin(x);sin(x)]; u=[u;0.2+sin(x);0.4+sin(x);0.6+sin(x);0.8+sin(x)]'; //start trying the symbols (negative values for the style) plot2d(x,u,style=[-9,-8,-7,-6,-5,-4,-3,-2,-1,0]) x=0:0.2:xmax; v=[1.4+sin(x);1.8+sin(x)]'; xset("mark size",5); plot2d(x,v,style=[-7,-8]) xset('default');

- Option
`frameflag`: is a scalar corresponding to :requirements ranges ranges ranges of a previous given by computed from actual plot rect arg x and y requested one 0 1 2 Computed for isometric 3 4 view Enlarged For pretty 5 6 axes Previous and current 7 8 plots merged - Option
`axesflag`controls the display of information on the frame around the plot :- 0 : nothing is drawn around the plot.
- 1 : axes are drawn, the y=axis is displayed on the left.
- 2 : the plot is surrounded by a box without tics.
- 3 : axes are drawn, the y=axis is displayed on the right.
- 4
:
axes are drawn centred in the middle of the frame box.
- 5
:
axes are drawn so as to cross at point
`(0,0)`. If point`(0,0)`does not lie inside the frame, axes will not appear on the graph.

- Option
`leg`: it is the string of the captions for the different plotted curves . This string is composed of fields separated by the`@`symbol: for example```module@phase''`(see example below). These strings are displayed under the plot with small segments recalling the styles of the corresponding curves. - Option
`rect`: it is a vector of 4 values specifying the boundaries of the plot`rect=[xmin,ymin,xmax,ymax]`. - Option
`nax`: it is a vector [nx,Nx,ny,Ny] where nx (ny) is the number of subgrads on the x (y) axis and Nx (Ny) is the number of graduations on the x (y) axis.

//captions for identifying the curves //controlling the boundaries of the plot and the tics on axes x=-5:0.1:5; y1=sin(x);y2=cos(x); X=[x;x]; Y=[y1;y2]; plot2d(X',Y',style=[-1 -3]',leg="caption1@caption2",... rect=[-5,-1,5,1],nax=[2,10,5,5]);

For different plots the simple commands without any argument show a demo
(e.g `plot2d3()` ).