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(str,x,y,[style,strf,leg,rect,nax])`

- index of
`plot2d`

:`i=missing,1,2,3,4`.For the different values of

`i`we have:`i=missing`: piecewise linear plotting`i=1`: as previous with possible logarithmic scales`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); xsetech([0.,0.,0.5,0.5],[-1,1,-1,1]); plot2d([t t],[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d'); titlepage('Piecewise linear'); // xsetech([0.5,0.,0.5,0.5],[-1,1,-1,1]); plot2d1('oll',t,[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d1'); titlepage('Logarithmic scale(s)'); // xsetech([0.,0.5,0.5,0.5],[-1,1,-1,1]); plot2d2('onn',t,[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d2'); titlepage('Piecewise constant'); // xsetech([0.5,0.5,0.5,0.5],[-1,1,-1,1]); plot2d3('onn',t,[1.5+0.2*sin(t) 2+cos(t)]); xtitle('Plot2d3') titlepage('Vertical bar plot') xset('default')

Figdirfigures/

- Parameter
`str`: it is the string`"abc"`:`str`is empty if`i`is missing.`a=e`: means empty; the values of`x`are not used; (The user must give a dummy value to`x`).`a=o`: means one; the x-values are the same for all the curves`a=g`: means general.`b=l`: a logarithmic scale is used on the X-axis`c=l`: a logarithmic scale is used on the Y-axis-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. - Parameter
`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).x=0:0.1:2*%pi; 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 color with the 2 following lines //sty=[-9,-8,-7,-6,-5,-4,-3,-2,-1,0]; //plot2d1('onn',x',u,sty,"111"," ",[0,-2,2*%pi,3],[2,10,2,10]); plot2d1('onn',x',u,... [9,8,7,6,5,4,3,2,1,0],"011"," ",[0,-2,2*%pi,3],[2,10,2,10]); x=0:0.2:2*%pi; v=[1.4+sin(x);1.8+sin(x)]'; xset("mark",1,5); plot2d1('onn',x',v,[7,8],"011"," ",[0,-2,2*%pi,3],[2,10,2,10]); xset('default');

Figdirfigures/

- Parameter
`strf`: it is a string of length 3`"xyz"`corresponding to :`x=1`: captions displayed`y=1`: the argument`rect`is used to specify the boundaries of the plot.

`rect=[xmin,ymin,xmax,ymax]``y=2`: the boundaries of the plot are computed`y=0`: the current boundaries`z=1`: an axis is drawn and the number of tics can be specified by the`nax`argument`z=2`: the plot is only surrounded by a box - Parameter
`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. - Parameter
`rect`: it is a vector of 4 values specifying the boundaries of the plot`rect=[xmin,ymin,xmax,ymax]`. - Parameter
`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=-%pi:0.3:%pi; y1=sin(x);y2=cos(x);y3=x; X=[x;x;x]; Y=[y1;y2;y3]; plot2d1("gnn",X',Y',[1 2 3]',"111","caption1@caption2@caption3",... [-3,-3,3,2],[2,20,5,5]);

Figdirfigures/

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