Date: Nov 6, 2012 5:46 AM
Author: Claude
Subject: Numerical integration with maxima

Dear readers

I would like to numerically integrate the function abs(sin(x)) over the
domain 0 to 2*pi.

I've defined the function

and then I called

integrate(f, x, 0, 2*pi)

But now I don't know how to numerically evaluate this integral.

Manually, it is easy to see that the result should be 4, but how to ask
maxima to compute this ?

Similarly, I cannot plot this function over the same domain. I've tried :

wxplot2d([abs(sin(x))], [x,0,6.28])$

which gives the expected graph, but, if I replace the value 6.28 by 2*pi,
wxmaxima says that

plotting: range must be of the form [variable, min, max]; found: [x,0,2*pi]

Can you please give me some advice?

Thank you in advance for your help