dgeqlf
dgeqlf - compute a QL factorization of a real M-by-N matrix A
SUBROUTINE DGEQLF( M, N, A, LDA, TAU, WORK, LDWORK, INFO)
INTEGER M, N, LDA, LDWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE DGEQLF_64( M, N, A, LDA, TAU, WORK, LDWORK, INFO)
INTEGER*8 M, N, LDA, LDWORK, INFO
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE GEQLF( [M], [N], A, [LDA], TAU, [WORK], [LDWORK], [INFO])
INTEGER :: M, N, LDA, LDWORK, INFO
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE GEQLF_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 dgeqlf(int m, int n, double *a, int lda, double *tau, int *info);
void dgeqlf_64(long m, long n, double *a, long lda, double *tau, long *info);
dgeqlf computes a QL factorization of a real M-by-N matrix A:
A = Q * L.
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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 lower triangle of the subarray
A(m-n+1:m,1:n) contains the N-by-N lower triangular matrix L;
if m <= n, the elements on and below the (n-m)-th
superdiagonal contain the M-by-N lower trapezoidal matrix L;
the remaining elements, with the array TAU, represent the
orthogonal matrix Q as a product of 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,N).
For optimum performance LDWORK >= N*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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