Fwd: RE: JAMA Improvement: Double JAMA's Speed

[boisvert@nist.gov]

Sender: kazar001@umn.edu
Subject: RE: JAMA Improvement: Double JAMA's Speed


why not adding that matrix class by yourself thus customizing JAMA...
thanks


On Nov 12 2007, Joe Hicklin wrote:

>Why just for small matrices?
>
>
>-----Original Message-----
>From: jama@nist.gov [mailto:jama@nist.gov] On Behalf Of
>boisvert@nist.gov
>Sent: Sunday, November 11, 2007 5:27 PM
>To: Multiple recipients of list
>Subject: Fwd: JAMA Improvement: Double JAMA's Speed
>
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>
>----- Forwarded message from "Castro, Giovanny A"
><> -----
>    Date: Fri, 9 Nov 2007 20:26:04 -0500
>    From: "Castro, Giovanny A" <>
> Subject: JAMA Improvement: Double JAMA's Speed
>      To: boisvert@nist.gov
>
>
>JAMA Authors, 
>
>
>I have a somewhat strange but valid proposal to improve the JAMA
>library:
>
>There should be a Matrix subclass for Matrix sizes under 15.
>Why? To take advantage of dramatic performance increases when using 
>one dimensional arrays at these sizes.
>
>For a 4x4 matrix a one dimensional array implementation is TWICE as fast
>as the JAMA implementation. 
>
>Why are 4x4 and 3x3 matrices important? They are critical to computer
>graphics and engineering applications. It would be my guess that a large
>percentage of people interested in a matrix library are interested in 
>using it in a computer graphics application - or in other engineering
>applications requiring scaling, translation and rotation.
>
>As it stands, JAMA is completely unacceptable for these applications.
>
>Especially in computer graphics applications, Java developers are
>already at a disadvantage compared to C/C++ (even Flash) developers. 
>
>If they could DOUBLE their Matrix and Vector multiplication (rotation)
>performance why would they choose JAMA?
>
>Unfortunately, implementing this proposal would require a redesigning of
>the JAMA library which is why I know this is a strange proposal.
>
>Developers cant subclass the Matrix class to do this themselves because
>it contains the double A[][] variable. Matrix might have to be an 
>abstract class with subclasses defining the data storage. There might 
>have to be a factory method by which to create matrices because
>it would have to return a one-dimensionally or two-dimensionally backed
>matrix depending on the dimensions...
>
>Obviously, I haven't considered the specifics of what would have to be
>done to JAMA to achieve this but I hope ive piqued someone curiosity 
>on this subject.  
>
>This thread is extremely chaotic but by the end the disparity between
>one-dimensional and two-dimensional arrays is shown:
>
>http://forum.java.sun.com/thread.jspa?threadID=5234721&tstart=0
>
>These are the results of JAMA vs a one-dimensional implementation doing 
>2 million matrix multiplication operations on 4x4 matrices (in
>milliseconds):
>
>One Dim Time: 3626
>JAMA Time: 7625
>
>One Dim Time: 3438
>JAMA Time: 7610
>
>One Dim Time: 3235
>JAMA Time: 7516 
>
>One Dim Time: 3235
>JAMA Time: 7532
>
>One Dim Time: 3250
>JAMA Time: 7610
> 
>
>Giovanny Castro
>
>
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