ssyev.f(3) [centos man page]
ssyev.f(3) LAPACK ssyev.f(3) NAME
ssyev.f - SYNOPSIS
Functions/Subroutines subroutine ssyev (JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, INFO) SSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices Function/Subroutine Documentation subroutine ssyev (characterJOBZ, characterUPLO, integerN, real, dimension( lda, * )A, integerLDA, real, dimension( * )W, real, dimension( * )WORK, integerLWORK, integerINFO) SSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices Purpose: SSYEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A. Parameters: JOBZ JOBZ is CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors. UPLO UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. N N is INTEGER The order of the matrix A. N >= 0. A A is REAL array, dimension (LDA, N) On entry, the symmetric matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A. On exit, if JOBZ = 'V', then if INFO = 0, A contains the orthonormal eigenvectors of the matrix A. If JOBZ = 'N', then on exit the lower triangle (if UPLO='L') or the upper triangle (if UPLO='U') of A, including the diagonal, is destroyed. LDA LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). W W is REAL array, dimension (N) If INFO = 0, the eigenvalues in ascending order. WORK WORK is REAL array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK LWORK is INTEGER The length of the array WORK. LWORK >= max(1,3*N-1). For optimal efficiency, LWORK >= (NB+2)*N, where NB is the blocksize for SSYTRD returned by ILAENV. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA. INFO INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: November 2011 Definition at line 133 of file ssyev.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 ssyev.f(3)
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dsyev.f(3) LAPACK dsyev.f(3) NAME
dsyev.f - SYNOPSIS
Functions/Subroutines subroutine dsyev (JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, INFO) DSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices Function/Subroutine Documentation subroutine dsyev (characterJOBZ, characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )W, double precision, dimension( * )WORK, integerLWORK, integerINFO) DSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices Purpose: DSYEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A. Parameters: JOBZ JOBZ is CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors. UPLO UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. N N is INTEGER The order of the matrix A. N >= 0. A A is DOUBLE PRECISION array, dimension (LDA, N) On entry, the symmetric matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A. On exit, if JOBZ = 'V', then if INFO = 0, A contains the orthonormal eigenvectors of the matrix A. If JOBZ = 'N', then on exit the lower triangle (if UPLO='L') or the upper triangle (if UPLO='U') of A, including the diagonal, is destroyed. LDA LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N). W W is DOUBLE PRECISION array, dimension (N) If INFO = 0, the eigenvalues in ascending order. WORK WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK LWORK is INTEGER The length of the array WORK. LWORK >= max(1,3*N-1). For optimal efficiency, LWORK >= (NB+2)*N, where NB is the blocksize for DSYTRD returned by ILAENV. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA. INFO INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: November 2011 Definition at line 133 of file dsyev.f. Author Generated automatically by Doxygen for LAPACK from the source code. Version 3.4.2 Tue Sep 25 2012 dsyev.f(3)