Testing Java Code in Maths Libraries 1

gistfile1.matlab

%% A translation of http://commons.apache.org/math/userguide/linear.html Example in section 3.2
%% Apache Commons Math is refered to as ACM

clear all; close all; clc;
% assume the jars in in the pwd, add to java class path
javaaddpath([pwd,'/commons-math3-3.0.jar']);
javaaddpath([pwd,'/octave.jar']);

% basenames for classes we'll be using
ACMBasename='org.apache.commons.math3.linear.';
octaveBasename='org.octave.';

% Create a real matrix with two rows and three columns
matrixData=[1.,2.,3.;2.,5.,3.]; % the data
tmp=javaObject([octaveBasename,'Matrix'],reshape(matrixData,1,6),[2,3]); % conversion temporary
m=javaObject([ACMBasename,'Array2DRowRealMatrix'],tmp.asDoubleMatrix()); % invoke ACM (double[][]) constructor

% One more with three rows, two columns
matrixData2=[1.,2.;3.,5.;1.,7.]; % the data
tmp=javaObject([octaveBasename,'Matrix'],reshape(matrixData2,1,6),[3,2]); % conversion temporary
n=javaObject([ACMBasename,'Array2DRowRealMatrix'],tmp.asDoubleMatrix()); % invoke ACM (double[][]) constructor


% Now multiply m by n
p = m.multiply(n); % ACM multiply
disp('ACM row count result:');
disp(['row dimension=',num2str(p.getRowDimension())])    % ACM result, rows = 2
disp(['row dimension=',num2str(p.getColumnDimension())])    % ACM result, columns = 2

disp('')
disp('ACM dgemm result:');
p.toString() % ACM print result

% ACM invert p, using LU decomposition
ludecomp = javaObject([ACMBasename,'LUDecomposition'],p); % ACM LUDecomposition class
pInverse = ludecomp.getSolver().getInverse(); % method invocation chaining also works in Octave! ACM inverse via LU.

disp('ACM inverse result:');
pInverse.toString()

% ship back to octave
ACMInverse=java2mat(pInverse.getData())


%% Now we do the same in native octave
octavep = matrixData * matrixData2;
disp('Octave dgemm result:');
octavep
disp('Octave inverse result:');
inv(octavep)

%% compute errors...
printf('Norm error Octave vs ACM = %20.12f\n',norm(inv(octavep)-ACMInverse))


%% helper function to make java double{[]...} into octave native
function [ret] = java2mat(v)
  n=length(v);
  ret=zeros(1,n);
  for k = 1:length(v)
    ret(k)=v(k);
  end
  ret =ret'