3-d graph with rainbow colors

plotfunc represents a pure imaginary expression i*E of two variables with a rainbow color depending on the value of z=E. This gives an easy way to find points having the same third coordinate.
The first arguments of plotfunc must be i*E instead of E, the remaining arguments are the same as for a real 3-d graph (cf 2.2.2) Input :

plotfunc(i*x*sin(y),[x=0..2,y=-pi..pi])

Output :

A piece of the surface z = x*sin(y) with rainbow colors

Remark
If you want the impression or the traduction Latex, you have to use :
Menu $\blacktriangleright$print $\blacktriangleright$Print(with Latex).