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Re: PDL::Complex question

by Anonymous Monk
on Apr 05, 2007 at 06:29 UTC ( [id://608421]=note: print w/replies, xml ) Need Help??


in reply to PDL::Complex question

You can install PDL-LinearAlgebra if you want to do linear algebra over complexes. Here is an example (note that if you load PDL::LinearALgebra the x operator (matrix multiplication in PDL) is overriden by the BLAS matrix multiplication and thus is complex aware. Here is a perldl session:
perldl> use PDL::Complex perldl> use PDL::LinearAlgebra perldl> $matrixM = cplx pdl [ [ 1+1*i, 2+1*i], [ 1-2*i, 2-1*i] ]; perldl> p $matrixM [ [1 +1i 2 +1i] [1 -2i 2 -1i] ] perldl> $matrixB_assigned_value = cplx pdl [ 5+8*i, 10-5*i ]; perldl> p $matrixB [ [ 5 +8i] [10 -5i] ] perldl> msolve($matrixM,$matrixB) [ [3+1i] [2+1i] ] [ [ 1 -2i 2 -1i] [-0.2 +0.6i 1.8 -0.4i] ] [2 2] 0 perldl> scalar msolve($matrixM,$matrixB) [ [3+1i] [2+1i] ] perldl> $matrixM->minv x $matrixB [ [3 +1i] [2 +1i] ]
In the last result we see from the amount of space between the real and imaginary part that the result is less precise.
----------------------------------------------------------- perldl> help minv minv Compute inverse of a general square matrix using LU factorization. Supports inplace and threading. Uses getrf and getri or cgetrf and cgetri from Lapack and return "inverse, info" in array context. PDL(inv) = minv(PDL) my $a = random(10,10); my $inv = minv($a); Docs from /usr/lib/perl5/PDL/LinearAlgebra.pm perldl> help msolve msolve Solve linear system of equations using LU decomposition. A * X = B Returns X in scalar context else X, LU, pivot vector and info. B is overwrited by X if its inplace flag is set. Supports threading. Uses gesv or cgesv from Lapack. (PDL(X), (PDL(LU), PDL(pivot), PDL(info))) = msolve(PDL(A), PDL(B) +) my $a = random(5,5); my $b = random(10,5); my $X = msolve($a, $b); Docs from /usr/lib/perl5/PDL/LinearAlgebra.pm

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