Claude
Posts:
2
Registered:
11/6/12


Re: Numerical integration with maxima
Posted:
Nov 7, 2012 3:21 PM


Thank you all for your help !
claude
James Cloos wrote:
>>>>>> "C" == Claude <claude@nospam.invalid> writes: > > Just a couple of notes: > > C> I've defined the function > C> f=abs(sin(x)) > > Use either: > > f:abs(sin(x)); > > or: > > f(x):=abs(sin(x)); > > C> integrate(f, x, 0, 2*pi) > > Use 2*%pi. > > C> But now I don't know how to numerically evaluate this integral. > > More importantly, integrate() is for symbolic integration. For > numerical integration use quad_qag() and the related functions. > > Try: > > quad_qag(abs(sin(x)), x, 0, 2*%pi, 2); > > for a 2nd order approximation. I get the result: > > [4.0, 4.440892098500626e14, 63, 0] > > the values in the list are theapproximation, the approx error, the > number of evaluations and an error code. 0 means no error. So the > result is 4.0 + 4.440892098500626e14. > > Try: > > ? quad_qag > > and: > > ?? QUADPACK > > in maxima. > > Or read the QUADPACK sections of the info or printable manual. > > JimC

