I don't have the cumtrapz function with FreeMat. I looked at Octave
and it's command isn't the same as MATLAB's. I wrote my own that
seems to work up to three dimensions anyway. Here it is inline:
% CUMTRAPZ - Cumulative trapezoidal numerical integration
%
% Usage
%
% Z = cumtrapz(Y)
% Z = cumtrapz(X,Y)
% Z = cumtrapz(Y,dim)
% Z = cumtrapz(X,Y,dim)
%
% Description
%
% Z = cumtrapz(Y) computes an approximation of the cumulative integral
of Y via
% the trapezoidal method with unit spacing. To compute the integral
with other
% than unit spacing, multiply Z by the spacing increment. Input Y can
be complex.
%
% For vectors, cumtrapz(Y) is a vector containing the cumulative
integral of Y.
%
% For matrices, cumtrapz(Y) is a matrix the same size as Y with the
cumulative
% integral over each column.
%
% For multidimensional arrays, cumtrapz(Y) works across the first
% nonsingleton dimension.
%
% Z = cumtrapz(X,Y) computes the cumulative integral of Y with respect
to X
% using trapezoidal integration. X and Y must be vectors of the same
length,
% or X must be a column vector and Y an array whose first nonsingleton
dimension
% is length(X). cumtrapz operates across this dimension. Inputs X and
Y can be
% complex.
%
% If X is a column vector and Y an array whose first nonsingleton
dimension
% is length(X), cumtrapz(X,Y) operates across this dimension.
%
% Z = cumtrapz(X,Y,dim) or cumtrapz(Y,dim) integrates across the
dimension of
% Y specified by scalar dim. The length of X must be the same as
size(Y,dim).
%
% Licensed under the GPL
% Copyright (C) 2010 Jonathan Weaver <jonw...@netscape.net>
function [A] = cumtrapz(x,y,dim)
% This program is free software; you can redistribute it and/or modify
it under
% the terms of the GNU General Public License as published by the Free
Software
% Foundation; either version 2 of the License, or (at your option) any
later
% version.
%
% This program is distributed in the hope that it will be useful, but
WITHOUT
% ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS
% FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more
% details.
%
% You should have received a copy of the GNU General Public License
along with
% this program; if not, write to the Free Software Foundation, Inc.,
% 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
if (nargin 1) %cumtrapz(y)
[y, dim] = shiftdim(x);
x = 1:size(y,1);
elseif(nargin 2) %cumtrapz(x,y) or cumtrapz(y,dim)
if(isscalar(y)) %cumtrapz(y,dim)
dim = y - 1;
y = shiftdim(x, dim);
x = 1:size(y,1);
else %cumtrapz(x,y);
[y, dim] = shiftdim(y);
if(length(x) ~= size(y,1))
error('The length of x must be equal to the length of
the first non-singleton dimension of y');
end
end
elseif(nargin 3) %cumtrapz(x,y,dim)
dim = dim - 1;
y = shiftdim(y,dim);
if(length(x) ~= size(y,1))
error('The length of x must be equal to the size(Y,dim)');
end
else
error('Invalid number of arguments');
end
n = size(y);
m = n(2:end);
a = [zeros([1 m]); (y(1:(n(1)-1),:,:,:,:,:)+y(2:n(1),:,:,:,:,:))/
2.*repmat(diff(x)', [1 m])];
A = shiftdim(cumsum(a),length(n) - dim);
end

On Nov 16, 6:02 am, Timothy Cyders <t.cyd...@gmail.com> wrote:
> If a numerical solution will suit you (indefinite integrals need not apply),
> you might look at the cumtrapz() function. Example: if you want to take the
> integral of y = x^2+4*x from 0 to 10,
>
> x = 0:0.01:10; % better resolution will give you more precise results
> y = x.^2+4*x;
> integral = cumtrapz(x,y) % gives a vector of values for the definite
> integral from x(1) to x(n). The last value integral(length(integral)) is the
> overall definite integral.
>
> TJ
>

> On Tue, Nov 16, 2010 at 2:38 AM, Eugene <gene...@gmail.com> wrote:
> > FreeMat does not support symbolic operations (yet). You need symbolic
> > algebra software, e.g. Maxima (http://maxima.sourceforge.net/).
>
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