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linalg_dsyev

Computes the eigenvalues of a symmetric real matrix.

Calling Sequence

d = linalg_dsyev ( A )
[R,d] = linalg_dsyev ( A )

Parameters

A :

a n-by-n matrix of doubles (real)

d :

a n-by-1 matrix of doubles (real), the eigenvalues

R :

a n-by-n matrix of doubles (real), the eigenvectors

Description

Computes the eigenvalues of a symmetric real matrix by calling LAPACK/DSYEV.

Examples

expected = (1:5)'
A = [
2.981136978768197388D+00,-1.521235057732858720D-01,-1.494446478130108780D+00, 3.455814188466865833D-02,3.801435242411201898D-01;
-1.521235057732858720D-01,1.643377375064559942D+00,-5.913719198065179317D-01, -5.355744671392123069D-01,2.280578576621679066D-01;
-1.494446478130108780D+00,-5.913719198065179317D-01,3.150577563873246945D+00, -1.800738655149962952D-01,-7.080430589262648455D-01;
3.455814188466863057D-02,-5.355744671392123069D-01,-1.800738655149962952D-01, 3.874373011768809771D+00,5.779580504744613600D-03;
3.801435242411201898D-01,2.280578576621679066D-01,-7.080430589262648455D-01, 5.779580504744613600D-03,3.350535070525185510D+00
];
d = linalg_dsyev(A)
d = gsort(d,"g","i")
// Compare with Scilab's:
spec(A)

// Get the eigenvectors too
[R,d] = linalg_dsyev ( A )
// Compare with Scilab's:
[R,D] = spec(A)

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