Discover how to handle plotting with Scilab with this example:

function f = myquadratic ( x )
 f = x.^2
 endfunction
 function f = myquadratic2 ( x )
 f = 2 * x.^2
 endfunction
 xdata = linspace ( 1 , 10 , 50 );
 ydata = myquadratic ( xdata );
 plot ( xdata , ydata , "+-" )
 ydata2 = myquadratic2 ( xdata );
 plot ( xdata , ydata2 , "o-" )
 xtitle ( "My title" , "X axis" , "Y axis" );

Read on scilab.io:

Getting started – Plotting