 
 
 
plotfunc takes two main arguments : an expression of two 
variables or a list of several expressions of two variables and the list of 
these two variables, where each variable may be replaced by
an equality variable=interval to specify the range for this variable
(if not specified, default values are taken from the graph configuration).
plotfunc accepts two optional arguments to specify 
the discretisation step in x and in y by
xstep=... and ystep=....
Alternatively one can specify the number of points used for the 
representation of the function with nstep= (instead of xstep and 
ystep).
plotfunc draws the surface(s) defined by z= the first argument.
Input :
^2+y^2,[x,y])Output :
^2+y^2Input :
Output :
Input :
Output :
Input :
Output :
Now an example where we specify the x and y discretisation step 
with xstep and ystep. Input :
Output :
Alternatively we may specify 
the number of points used for the representation of the
function with nstep instead of xstep and ystep, input :
Output :
Remarks
 
 
