dgeqp3
dgeqp3 - compute a QR factorization with column pivoting of a matrix A
SUBROUTINE DGEQP3( M, N, A, LDA, JPVT, TAU, WORK, LWORK, INFO)
INTEGER M, N, LDA, LWORK, INFO
INTEGER JPVT(*)
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE DGEQP3_64( M, N, A, LDA, JPVT, TAU, WORK, LWORK, INFO)
INTEGER*8 M, N, LDA, LWORK, INFO
INTEGER*8 JPVT(*)
DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*)
SUBROUTINE GEQP3( [M], [N], A, [LDA], JPVT, TAU, [WORK], [LWORK],
* [INFO])
INTEGER :: M, N, LDA, LWORK, INFO
INTEGER, DIMENSION(:) :: JPVT
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE GEQP3_64( [M], [N], A, [LDA], JPVT, TAU, [WORK], [LWORK],
* [INFO])
INTEGER(8) :: M, N, LDA, LWORK, INFO
INTEGER(8), DIMENSION(:) :: JPVT
REAL(8), DIMENSION(:) :: TAU, WORK
REAL(8), DIMENSION(:,:) :: A
#include <sunperf.h>
void dgeqp3(int m, int n, double *a, int lda, int *jpvt, double *tau, int *info);
void dgeqp3_64(long m, long n, double *a, long lda, long *jpvt, double *tau, long *info);
dgeqp3 computes a QR factorization with column pivoting of a
matrix A: A*P = Q*R using Level 3 BLAS.
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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, the upper triangle of the array contains the
min(M,N)-by-N upper trapezoidal matrix R; the elements below
the diagonal, together with the array TAU, represent the
orthogonal matrix Q as a product of min(M,N) elementary
reflectors.
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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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* JPVT (input/output)
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On entry, if JPVT(J).ne.0, the J-th column of A is permuted
to the front of A*P (a leading column); if JPVT(J)=0,
the J-th column of A is a free column.
On exit, if JPVT(J)=K, then the J-th column of A*P was the
the K-th column of A.
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* TAU (output)
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The scalar factors of the elementary reflectors.
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* WORK (workspace)
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On exit, if INFO=0, WORK(1) returns the optimal LWORK.
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* LWORK (input)
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The dimension of the array WORK. LWORK >= 3*N+1.
For optimal performance LWORK >= 2*N+( N+1 )*NB, where NB
is the optimal 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.
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* INFO (output)
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