From: Link Davis
Subject: matrix inversion
Date: 
Message-ID: <9ji4ea$m7o$1@slb7.atl.mindspring.net>
How realistic would it be to convert a Fortran 77 program to ACL6?

In particular, how do the matrix inversion capabilities compare?

And if they do not compare, is it possible to create them using Lisp alone?

From: Kaz Kylheku
Subject: Re: matrix inversion
Date: 
Message-ID: <eX077.21474$zb.382796@news1.rdc1.bc.home.com>
In article <············@slb7.atl.mindspring.net>, Link Davis wrote:
>How realistic would it be to convert a Fortran 77 program to ACL6?
>
>In particular, how do the matrix inversion capabilities compare?
>
>And if they do not compare, is it possible to create them using Lisp alone?

You have all the numeric capabilities you need to implement matrix
inversion. Matrix inversion is not a simple problem; the results are
sensitive to the method that is applied due to floating point truncation
issues.

Because Common Lisp has built-in rational types, you could actually
perform an *exact* inverse using straightforward Gaussian elimination
on a matrix containing only rationals. Yet that same code could also
compute a reasonable approximation of a floating-point matrix inverse,
depending on the input.
From: Link Davis
Subject: Re: matrix inversion
Date: 
Message-ID: <9ji8ho$1rh$1@slb1.atl.mindspring.net>
Thank you very much.


Kaz Kylheku wrote in message ...
>In article <············@slb7.atl.mindspring.net>, Link Davis wrote:
>>How realistic would it be to convert a Fortran 77 program to ACL6?
>>
>>In particular, how do the matrix inversion capabilities compare?
>>
>>And if they do not compare, is it possible to create them using Lisp
alone?
>
>You have all the numeric capabilities you need to implement matrix
>inversion. Matrix inversion is not a simple problem; the results are
>sensitive to the method that is applied due to floating point truncation
>issues.
>
>Because Common Lisp has built-in rational types, you could actually
>perform an *exact* inverse using straightforward Gaussian elimination
>on a matrix containing only rationals. Yet that same code could also
>compute a reasonable approximation of a floating-point matrix inverse,
>depending on the input.
From: Link Davis
Subject: Re: matrix inversion
Date: 
Message-ID: <9ji8k1$rts$1@slb1.atl.mindspring.net>
Thanks!

>Because Common Lisp has built-in rational types, you could actually
>perform an *exact* inverse using straightforward Gaussian elimination
>on a matrix containing only rationals. Yet that same code could also
>compute a reasonable approximation of a floating-point matrix inverse,
>depending on the input.
From: Jacek Generowicz
Subject: Re: matrix inversion
Date: 
Message-ID: <g0y9pewypw.fsf@scumbag.ecs.soton.ac.uk>
"Link Davis" <·········@mindspring.com> writes:

> How realistic would it be to convert a Fortran 77 program to ACL6?
> 
> In particular, how do the matrix inversion capabilities compare?
> 
> And if they do not compare, is it possible to create them using Lisp alone?

Have you come across matlisp ?

http://matlisp.sourceforge.net/

Jacek
From: Link Davis
Subject: Re: matrix inversion
Date: 
Message-ID: <9jmpqt$lip$1@nntp9.atl.mindspring.net>
>Have you come across matlisp ?
>
>http://matlisp.sourceforge.net/
>
>Jacek

Not until you mentioned it.

Thanks for the great link.

However, I hope to use Lisp exclusively.

Speed is not deciding factor since this is a learning project with modest
initial applications in mind.
From: Ole Rohne
Subject: Re: matrix inversion
Date: 
Message-ID: <ebwae1tm1lq.fsf@lxplus022.cern.ch>
"Link Davis" <·········@mindspring.com> writes:

> However, I hope to use Lisp exclusively.

Check out CMU's ai-repository:

<http://www-cgi.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/lisp/code/math/matrix>

	Ole
From: Link Davis
Subject: Re: matrix inversion
Date: 
Message-ID: <9jo370$sh2$1@slb5.atl.mindspring.net>
>Check out CMU's ai-repository:
>
><http://www-cgi.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/lisp/code/m
ath/matrix>
>
> Ole

Thank you.

I wonder... are there any pure-Lisp FEA packages?
From: Jacek Generowicz
Subject: Re: matrix inversion
Date: 
Message-ID: <g0g0bk2g7j.fsf@scumbag.ecs.soton.ac.uk>
"Link Davis" <·········@mindspring.com> writes:

> I wonder... are there any pure-Lisp FEA packages?

There will be when I've finished :-)   (Don't hold your breath.)