error plotting an ellipse

[Huub]

Hi,

Using scilab 4.1 on NetBSD/i386 4.0.1, I'm trying to plot an ellipse with 
equation (x^2/9) + (y^2/4) = 1. However, I get the error "inconsistent 
addition" which seems to be related to "+" and everything behind it: 

plot(((x**2)/9)+((y**2)/4)=1)

(I made a snapshot, but Pan seems unable to insert it.) What is the 
reason for the error?

Thanks for helping out.

Huub