3-d graph with rainbow colors

### 3.2.3 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 3.2.2) 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``▸``print``▸``Print(with Latex)`.