plot2d



Hello,

This is a newbee's problem: I just tried wxMaxima 0.8.4 and entered as 
in the manual (chap. 1, Introduction to Maxima) the following command:

plot2d(sin(x)/x,[x,-20,20])

I obtained the plot but on ending the plot window there appeared a 
message in the main window:

plot2d: expression evaluates to non-numeric value somewhere in 
plotting range.

What had I done wrongly? Thanks for your help in advance.

M. K. Shen