sorgtr(3P) Sun Performance Library sorgtr(3P)NAMEsorgtr - generate a real orthogonal matrix Q which is defined as the
product of n-1 elementary reflectors of order N, as returned by SSYTRD
SYNOPSIS
SUBROUTINE SORGTR(UPLO, N, A, LDA, TAU, WORK, LWORK, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDA, LWORK, INFO
REAL A(LDA,*), TAU(*), WORK(*)
SUBROUTINE SORGTR_64(UPLO, N, A, LDA, TAU, WORK, LWORK, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDA, LWORK, INFO
REAL A(LDA,*), TAU(*), WORK(*)
F95 INTERFACE
SUBROUTINE ORGTR(UPLO, [N], A, [LDA], TAU, [WORK], [LWORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDA, LWORK, INFO
REAL, DIMENSION(:) :: TAU, WORK
REAL, DIMENSION(:,:) :: A
SUBROUTINE ORGTR_64(UPLO, [N], A, [LDA], TAU, [WORK], [LWORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDA, LWORK, INFO
REAL, DIMENSION(:) :: TAU, WORK
REAL, DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void sorgtr(char uplo, int n, float *a, int lda, float *tau, int
*info);
void sorgtr_64(char uplo, long n, float *a, long lda, float *tau, long
*info);
PURPOSEsorgtr generates a real orthogonal matrix Q which is defined as the
product of n-1 elementary reflectors of order N, as returned by SSYTRD:
if UPLO = 'U', Q = H(n-1) . . . H(2)H(1),
if UPLO = 'L', Q = H(1)H(2) . . . H(n-1).
ARGUMENTS
UPLO (input)
= 'U': Upper triangle of A contains elementary reflectors
from SSYTRD; = 'L': Lower triangle of A contains elementary
reflectors from SSYTRD.
N (input) The order of the matrix Q. N >= 0.
A (input/output)
On entry, the vectors which define the elementary reflectors,
as returned by SSYTRD. On exit, the N-by-N orthogonal matrix
Q.
LDA (input)
The leading dimension of the array A. LDA >= max(1,N).
TAU (input)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by SSYTRD.
WORK (workspace)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input)
The dimension of the array WORK. LWORK >= max(1,N-1). For
optimum performance LWORK >= (N-1)*NB, where NB is the opti‐
mal blocksize.
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 (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
6 Mar 2009 sorgtr(3P)