.TH "SRC/cheevd.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*- .ad l .nh .SH NAME SRC/cheevd.f .SH SYNOPSIS .br .PP .SS "Functions/Subroutines" .in +1c .ti -1c .RI "subroutine \fBcheevd\fP (jobz, uplo, n, a, lda, w, work, lwork, rwork, lrwork, iwork, liwork, info)" .br .RI "\fB CHEEVD computes the eigenvalues and, optionally, the left and/or right eigenvectors for HE matrices\fP " .in -1c .SH "Function/Subroutine Documentation" .PP .SS "subroutine cheevd (character jobz, character uplo, integer n, complex, dimension( lda, * ) a, integer lda, real, dimension( * ) w, complex, dimension( * ) work, integer lwork, real, dimension( * ) rwork, integer lrwork, integer, dimension( * ) iwork, integer liwork, integer info)" .PP \fB CHEEVD computes the eigenvalues and, optionally, the left and/or right eigenvectors for HE matrices\fP .PP \fBPurpose:\fP .RS 4 .PP .nf !> !> CHEEVD computes all eigenvalues and, optionally, eigenvectors of a !> complex Hermitian matrix A\&. If eigenvectors are desired, it uses a !> divide and conquer algorithm\&. !> !> .fi .PP .RE .PP \fBParameters\fP .RS 4 \fIJOBZ\fP .PP .nf !> JOBZ is CHARACTER*1 !> = 'N': Compute eigenvalues only; !> = 'V': Compute eigenvalues and eigenvectors\&. !> .fi .PP .br \fIUPLO\fP .PP .nf !> UPLO is CHARACTER*1 !> = 'U': Upper triangle of A is stored; !> = 'L': Lower triangle of A is stored\&. !> .fi .PP .br \fIN\fP .PP .nf !> N is INTEGER !> The order of the matrix A\&. N >= 0\&. !> .fi .PP .br \fIA\fP .PP .nf !> A is COMPLEX array, dimension (LDA, N) !> On entry, the Hermitian 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\&. !> .fi .PP .br \fILDA\fP .PP .nf !> LDA is INTEGER !> The leading dimension of the array A\&. LDA >= max(1,N)\&. !> .fi .PP .br \fIW\fP .PP .nf !> W is REAL array, dimension (N) !> If INFO = 0, the eigenvalues in ascending order\&. !> .fi .PP .br \fIWORK\fP .PP .nf !> WORK is COMPLEX array, dimension (MAX(1,LWORK)) !> On exit, if INFO = 0, WORK(1) returns the optimal LWORK\&. !> .fi .PP .br \fILWORK\fP .PP .nf !> LWORK is INTEGER !> The length of the array WORK\&. !> If N <= 1, LWORK must be at least 1\&. !> If JOBZ = 'N' and N > 1, LWORK must be at least N + 1\&. !> If JOBZ = 'V' and N > 1, LWORK must be at least 2*N + N**2\&. !> !> If LWORK = -1, then a workspace query is assumed; the routine !> only calculates the optimal sizes of the WORK, RWORK and !> IWORK arrays, returns these values as the first entries of !> the WORK, RWORK and IWORK arrays, and no error message !> related to LWORK or LRWORK or LIWORK is issued by XERBLA\&. !> .fi .PP .br \fIRWORK\fP .PP .nf !> RWORK is REAL array, dimension (MAX(1,LRWORK)) !> On exit, if INFO = 0, RWORK(1) returns the optimal LRWORK\&. !> .fi .PP .br \fILRWORK\fP .PP .nf !> LRWORK is INTEGER !> The dimension of the array RWORK\&. !> If N <= 1, LRWORK must be at least 1\&. !> If JOBZ = 'N' and N > 1, LRWORK must be at least N\&. !> If JOBZ = 'V' and N > 1, LRWORK must be at least !> 1 + 5*N + 2*N**2\&. !> !> If LRWORK = -1, then a workspace query is assumed; the !> routine only calculates the optimal sizes of the WORK, RWORK !> and IWORK arrays, returns these values as the first entries !> of the WORK, RWORK and IWORK arrays, and no error message !> related to LWORK or LRWORK or LIWORK is issued by XERBLA\&. !> .fi .PP .br \fIIWORK\fP .PP .nf !> IWORK is INTEGER array, dimension (MAX(1,LIWORK)) !> On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK\&. !> .fi .PP .br \fILIWORK\fP .PP .nf !> LIWORK is INTEGER !> The dimension of the array IWORK\&. !> If N <= 1, LIWORK must be at least 1\&. !> If JOBZ = 'N' and N > 1, LIWORK must be at least 1\&. !> If JOBZ = 'V' and N > 1, LIWORK must be at least 3 + 5*N\&. !> !> If LIWORK = -1, then a workspace query is assumed; the !> routine only calculates the optimal sizes of the WORK, RWORK !> and IWORK arrays, returns these values as the first entries !> of the WORK, RWORK and IWORK arrays, and no error message !> related to LWORK or LRWORK or LIWORK is issued by XERBLA\&. !> .fi .PP .br \fIINFO\fP .PP .nf !> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !> > 0: if INFO = i and JOBZ = 'N', then the algorithm failed !> to converge; i off-diagonal elements of an intermediate !> tridiagonal form did not converge to zero; !> if INFO = i and JOBZ = 'V', then the algorithm failed !> to compute an eigenvalue while working on the submatrix !> lying in rows and columns INFO/(N+1) through !> mod(INFO,N+1)\&. !> .fi .PP .RE .PP \fBAuthor\fP .RS 4 Univ\&. of Tennessee .PP Univ\&. of California Berkeley .PP Univ\&. of Colorado Denver .PP NAG Ltd\&. .RE .PP \fBFurther Details:\fP .RS 4 Modified description of INFO\&. Sven, 16 Feb 05\&. .RE .PP \fBContributors:\fP .RS 4 Jeff Rutter, Computer Science Division, University of California at Berkeley, USA .RE .PP .PP Definition at line \fB196\fP of file \fBcheevd\&.f\fP\&. .SH "Author" .PP Generated automatically by Doxygen for LAPACK from the source code\&.