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Re: Integrating a function with many arguments over one varible.
From: |
Henry F. Mollet |
Subject: |
Re: Integrating a function with many arguments over one varible. |
Date: |
Fri, 26 Aug 2005 09:09:42 -0700 |
User-agent: |
Microsoft-Entourage/11.1.0.040913 |
Not sure if this helps but Octave-forge does have quadl.
Henry
octave:2> help quadl
quadl is the user-defined function from the file
/usr/local/share/octave/2.1.71/site/m/octave-forge/general/quadl.m
QUADL Numerically evaluate integral using adaptive
Lobatto rule.
Q=QUADL('F',A,B) approximates the integral of
F(X) from A to B to machine precision. 'F' is a
string containing the name of the function. The
function F must return a vector of output values if
given a vector of input values.
Q=QUADL('F',A,B,TOL) integrates to a relative
error of TOL.
Q=QUADL('F',A,B,TOL,TRACE) displays the left
end point of the current interval, the interval
length, and the partial integral.
Q=QUADL('F',A,B,TOL,TRACE,P1,P2,...) allows
coefficients P1, ... to be passed directly to the
function F: G=F(X,P1,P2,...). To use default values
for TOL or TRACE, one may pass the empty matrix ([]).
W. Gander and W. Gautschi, Adaptive Quadrature - Revisited,
BIT Vol. 40, No. 1, March 2000, pp. 84--101.
http://www.inf.ethz.ch/personal/gander/
on 8/26/05 4:14 AM, address@hidden at address@hidden
wrote:
> I need to find the integral of f(x, y1, ..., yn), over the variable x,
> between 2 limits. I read that quadl in Matlab can do it simply, you only
> have to add the values of the parameters y1, ..., yn at the end, when you
> use quadl. I tried to do the same with quad in Octave, but it did not
> work.
>
> I can't define "by hand" a function g(x) so that g(x) = f(x, y1, ..., yn),
> and use quad with g(x), because in fact I need to find the values
> y1,...,yn that minimize such quadrature along x.
>
> Can someone help me?
>
> Thank you.
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