Linear system solver in D?

BCS ao at
Tue Feb 19 18:05:52 PST 2008

Reply to Bill,

> BCS wrote:
>> thanks, both or you, I'll look at those. Performance isn't that big
>> an issue as I'm only looking at about 15-30 equations and a few
>> minutes run time would be ok, but I'm going to have to run ~1500
>> passes through it.
> Are the equations the same each time?  I.e. do the a_m1 coeffs stay
> the same for all 1500 passes? or do they change each time?
> If they stay the same then you can factorize A once and do the much
> faster back-substitution 1500 times.

no such luck. This will be part of a newton Newton–Raphson non-linear solver 
for doing a numerical approximation of a system of non-linear differential 
equations. (a.k.a. bad, worse, nasty)

> If you don't care about performance just search the web for some
> C/C++/C#/Java code for Gaussian Elimination with Partial (or better,
> Full) pivoting.  It should be pretty straightforward to port.

performance takes a back seat to complexity but is still an issue. OTOH generating 
bindings for canned C code is less complex than porting it.

> Then you won't have to worry about dependencies and building

building and what not isn't a big issue.

> Actually you didn't say, but are m and n not the same?

On the way out the door after posting that I relized that I put in NxM rather 
than NxN. oops.

> --bb

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