On Mon, Apr 4, 2011 at 7:21 PM, bzink <william.z...@juno.com> wrote:
> Hello, Could someone who is familiar with the Java package explain how to
> pass a 2D octave array to a java method?
>
> When I try the following java method
>
> package naa.tools;
> public class Matlab
> {
> static public String isa(double [][] x) { return "double [][]";}
> static public String isa(Object x) {return x.getClass().getName();}
> }
>
> on the octave command-line with a 2D matrix, I get, for example,
>
> octave-3.2.4.exe:4> java_invoke("naa.tools.Matlab", "isa", [1 2; 3 4])
> ans = org.octave.OctaveReference
>
> So if a 2D octave matrix does not map directly to a java double [][], is
> there a method to test whether this OctaveReference object refers to a
> matrix, and if so, to convert that reference to a double[][] version of the
> original argument?
>
> I use java-1.2.7 on the Octave-Forge Windows v3.2.4 binary.
You can't do much with an OctaveReference object. This was only a way
to pass octave objects to Java such that they can be passed back to
octave from Java.
By default, the java module will only convert one-dimensional matrices
(row or column vector) into double[] objects. However, other conversions
are available when setting the java_convert_matrix variable to 1, as in
java_convert_matrix(1)
That function returns the previous value of the internal flag, such that you
can write:
flag = java_convert_matrix(1)
unwind_protect
# do something
unwind_protect_cleanup
java_convert_matrix(flag)
end_unwind_protect
When this flag is set, octave matrices will be converted to org.octave.Matrix
objects. That class provides some basic functionalities, such as the method
"asDoubleMatrix()" which converts the Matrix object into double[][], provided
that the matrix is 2D. Note also that Matrix objects will also be automatically
converted to equivalent octave matrices when returning back to octave world.
The java->octave matrix conversion is also controlled by the
java_unsigned_conversion
flag (similar syntax as java_convert_matrix). When this flag is set,
Matrix objects
whose internal data array is byte[] or int[] will be converted into
uint8 and uint32
octave matrices. Otherwise, they will be converted into int8 and int32 matrices.
If you want more information about the Matrix class, see the source code
in
http://octave.svn.sourceforge.net/viewvc/octave/trunk/octave-forge/extra/java/src/org/octave/Matrix.java?revision=HEAD&view=markup
Hope this helps.
Michael.
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