Re: [Lapackpp-devel] Latridiagatdouble

[Do bi <mrc...@ya...>]

Thanks Chris for the small code. Brilliant!

Christian Stimming <sti...@tu...> wrote:  -----BEGIN PGP SIGNED MESSAGE-----
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Do bi schrieb:
> Hi. You briefly explained with enough code how to create a tridiagonal
> matrix on
> http://lapackpp.sourceforge.net/html/classLaTridiagMatDouble.html#_details
> which is 
> LaVectorDouble newdiag(N);
> newdiag(0) = ...;
> LaTriagMatDouble triagmat(N);
> triagmat.diag(0).inject(newdiag); // correct
> // but don't write this:
> triagmat.diag(0) = newdiag; // wrong!
> and easily understood and very helpful. Can you please write a similar
> size of code to solve a tridiagonal matrix?

Sure:

#include // for LaTridiagFactDouble class

// define A
LaTridiagMatDouble A(N);
A.diag(0).inject(...); // fill the matrix with values
// define X and B
LaGenMatDouble B(N,1);
B = ...; // fill B with values from somewhere
// To solve Ax=b:
LaTridiagFactDouble Afact;
LaGenMatDouble X(N,1);
LaTridiagMatFactorize(A, Afact); // calculate LU factorization
LaLinearSolve(Afact, X, B); // solve; result is in X

Regards,

Christian

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