From help-octave-request at bevo dot che dot wisc dot edu Sat Apr 13 17:00:27 2002
Subject: confusion about dld's
From: Heber Farnsworth <farnsworth at olin dot wustl dot edu>
To: help-octave at bevo dot che dot wisc dot edu
Date: Sat, 13 Apr 2002 16:59:01 -0500

I have written several dld functions in the past but now I'm faced with 
having to write a quite complex one and I'm bumping up against my 
ignorance.  I'm no C++ wiz and I'm getting confused about 
octave_values.  I was trying to compile my function and I was surprised 
to find that it appears that something like A*B*C, where A and C are 
matrices and B is a diagonal matrix, gives an octave_value and not a 
Matrix.  Perhaps I'm misinterpretting the messages I'm getting from gcc.

In the past when I write dld functions I take the octave_value_list args 
and pick out the components and make them either Matrices, vectors, or 
doubles as seems appropriate.  Then I convert the object to be return in 
to octave_values.  In the middle of the program I've never dealt with 
octave_values.  Do I have to?  It seems like this is not an easy thing 
to deal with.  Things like sums, inverses, transposes, etc. don't seem 
to work on them.   Is that right?

I wouldn't mess with this complicated of a function but the non C++ 
version of this function takes 11 hours to run and I need to call this 
function several hundred times in the project I'm doing now so I have to 
find a faster way.

Heber



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