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! Eigenvalues of a real symmetric / complex hermitian matrix
program example_eigvalsh
use stdlib_linalg, only: eigvalsh
implicit none
real, allocatable :: A(:,:),lambda(:)
complex, allocatable :: cA(:,:)
! Decomposition of this symmetric matrix
! NB Fortran is column-major -> transpose input
A = transpose(reshape( [ [2, 1, 4], &
[1, 3, 5], &
[4, 5, 4] ], [3,3] ))
! Note: real symmetric matrices have real (orthogonal) eigenvalues and eigenvectors
lambda = eigvalsh(A)
print *, 'Symmetric matrix eigenvalues: ',lambda
! Complex hermitian matrices have real (orthogonal) eigenvalues and complex eigenvectors
cA = A
lambda = eigvalsh(cA)
print *, 'Hermitian matrix eigenvalues: ',lambda
end program example_eigvalsh
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