Re: using ublas to solve linear systems?

From: jhrwalter (jhr.walter_at_[hidden])
Date: 2002-11-10 14:52:52

--- In Boost-Users_at_y..., "deane_yang" <Deane_Yang_at_y...> wrote:
> I'm trying to see if I can use ublas to solve a linear system of 
equations.

Yes, you can use it to write a lu factorization, for example.

> Digging through the documentation, I find a description of a 
function
> called 'solve" that says "Solves a linear equation for a triangular 
matrix."
> There is also a formula,
> 
> B = solve(A, B, tag)   <------>      B <- A-1 B

At least the -1 is superscripted in the HTML docs, meaning the 
inverse of the matrix AFAIK.

> But I just don't know what any of this means (even though I am a 
> mathematician and quite fluent in linear algebra).
> 
> So
> a) can ublas be used (without me implementing any additional
> algorithms) to solve a linear system of equations?

No.

> b) what exactly does the function solve do?

It's the usual BLAS (see for example www.netlib.org/blas) triangular 
solver (sorry for the repetition) used in the 
forward/backsubstitution step of lu for example.

Best regards

Joerg