dgecon dgecov dgels dgesv dlange dlansy dpocon dposv dsyev

dsyev() function dsyev ( jobz::Char  , uplo::Char  , n::Integer  , a::Array{Float64}  , w::Array{Float64}    ) Eigenvalues and eigenvectors of a symmetric matrix Purpose dsyev computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A. Returns info (Int32) = 0: Successful exit = -1: The argument jobz had an illegal value (jobz != 'V' nor 'N') = -2: The argument uplo had an illegal value (uplo != 'U' nor 'L') = -3: The argument n had an illegal value (n < 0) = -4: The argument a is invalid. = -5: The argument w is invalid. = i > 0: The algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. Parameters [in] jobz = 'N': Compute eigenvalues only. = 'V': Compute eigenvalues and eigenvectors. [in] uplo = 'U': Upper triangle of A is stored. = 'L': Lower triangle of A is stored. [in] n Order of the matrix A. (n >= 0) (If n = 0, returns without computation) [in,out] a 2-dimensional array (Float64, n x n) [in] n x n symmetric matrix A. The upper or lower triangular part is to be stored in accordance with uplo. [out] jobz = 'V': If info = 0, a contains the orthonormal eigenvectors of the matrix A.   jobz = 'N': The lower triangle (if uplo = 'L') or the upper triangle (if uplo = 'U') of a, including the diagonal, is destroyed. [out] w 1-dimensional array (Float64, n) If info = 0, the eigenvalues in ascending order. Reference LAPACK Example Program Compute all eigenvalues and eigenvectors of the symmetric matrix A, where ( 2.20 -0.11 -0.32 ) A = ( -0.11 2.93 0.81 ) ( -0.32 0.81 2.37 ) function TestDsyev() n = 3 a = [ 2.2 -0.11 -0.32; 0.0 2.93 0.81; 0.0 0.0 2.37 ] w = Vector{Cdouble}(undef, n) info = dsyev('V', 'U', n, a, w) println("w = ", w, ", info = ", info) println("a:") println(a) end Example Results > TestDsyev() w = [1.7070595491104588, 2.22943643244226, 3.5635040184472837], info = 0 a: [-0.3993220772133821 0.894521385341403 -0.20093125644579898; 0.4810264443405481 0.3909945886772715 0.7846889775383503; -0.7804841052161664 -0.2166903846320573 0.586421212707156]