Re: [Matlisp-users] Cholesky factorization

[rif <ri...@MI...>]

> >>>>> "rif" == rif  <ri...@MI...> writes:
> 
>     rif> I assume it would be a lot of work to expose the ability to do work in
>     rif> single-precision floating point rather than double?
> 
> I suppose with some hacking of the macros we could make it work,
> assuming that single-precision routines always want single-precision
> arrays and numbers.
> 
> This would be a bit tedious, and I'm reluctant to do this, however.  I
> decided long ago that double-precision almost always allowed me to
> ignore round-off issues for the things I do.  The extra time and
> memory were not an issue.  Are you on an x86?  Then single-precision
> only buys you memory.
> 
> Ray

Yeah, I'm on x-86 right now.  I agree that it only buys me memory, but
it buys me a lot of memory, which in turn leads to the ability to deal
with systems that are O(sqrt(n)) larger.  On the other hand, I do
agree that it's not worth it if it's a lot of tedious work.

In a related question, how do I save a matrix of doubles to a file
(under CMUCL)?  For arrays of floats, I'm using something like

(write-byte (kernel:single-float-bits (aref arr i j)) str)

What's the equivalent for matlisp matrices?  I want to read and store
them in files.

Cheers,

rif