dgerqf
dgerqf - compute an RQ factorization of a real M-by-N matrix A
SUBROUTINE DGERQF( M, N, A, LDA, TAU, WORK, LDWORK, INFO)
INTEGER M, N, LDA, LDWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE DGERQF_64( M, N, A, LDA, TAU, WORK, LDWORK, INFO)
INTEGER*8 M, N, LDA, LDWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE GERQF( [M], [N], A, [LDA], TAU, [WORK], [LDWORK], [INFO])
INTEGER :: M, N, LDA, LDWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE GERQF_64( [M], [N], A, [LDA], TAU, [WORK], [LDWORK],
* [INFO])
INTEGER(8) :: M, N, LDA, LDWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
#include <sunperf.h>
void dgerqf(int m, int n, double *a, int lda, double *tau, int *info);
void dgerqf_64(long m, long n, double *a, long lda, double *tau, long *info);
dgerqf computes an RQ factorization of a real M-by-N matrix A:
A = R * Q.
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* M (input)
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The number of rows of the matrix A. M >= 0.
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* N (input)
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The number of columns of the matrix A. N >= 0.
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* A (input/output)
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On entry, the M-by-N matrix A.
On exit,
if m <= n, the upper triangle of the subarray
A(1:m,n-m+1:n) contains the M-by-M upper triangular matrix R;
if m >= n, the elements on and above the (m-n)-th subdiagonal
contain the M-by-N upper trapezoidal matrix R;
the remaining elements, with the array TAU, represent the
orthogonal matrix Q as a product of min(m,n) elementary
reflectors (see Further Details).
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* LDA (input)
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The leading dimension of the array A. LDA >= max(1,M).
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* TAU (output)
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The scalar factors of the elementary reflectors (see Further
Details).
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* WORK (workspace)
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On exit, if INFO = 0, WORK(1) returns the optimal LDWORK.
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* LDWORK (input)
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The dimension of the array WORK. LDWORK >= max(1,M).
For optimum performance LDWORK >= M*NB, where NB is
the optimal blocksize.
If LDWORK = -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 LDWORK is issued by XERBLA.
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* INFO (output)
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