dgeqrfp - N matrix A: A = Q * R
SUBROUTINE DGEQRFP(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER INFO, LDA, LWORK, M, N DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*) SUBROUTINE DGEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER*8 INFO, LDA, LWORK, M, N DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*) F95 INTERFACE SUBROUTINE GEQRFP(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER :: M, N, LDA, LWORK, INFO REAL(8), DIMENSION(:,:) :: A REAL(8), DIMENSION(:) :: WORK SUBROUTINE GEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER(8) :: M, N, LDA, LWORK, INFO REAL(8), DIMENSION(:,:) :: A REAL(8), DIMENSION(:) :: WORK C INTERFACE #include <sunperf.h> void dgeqrfp (int m, int n, double *a, int lda, double *tau, int *info); void dgeqrfp_64 (long m, long n, double *a, long lda, double *tau, long *info);
Oracle Solaris Studio Performance Library dgeqrfp(3P) NAME dgeqrfp - compute a QR factorization of a real M-by-N matrix A: A = Q * R SYNOPSIS SUBROUTINE DGEQRFP(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER INFO, LDA, LWORK, M, N DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*) SUBROUTINE DGEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER*8 INFO, LDA, LWORK, M, N DOUBLE PRECISION A(LDA,*), TAU(*), WORK(*) F95 INTERFACE SUBROUTINE GEQRFP(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER :: M, N, LDA, LWORK, INFO REAL(8), DIMENSION(:,:) :: A REAL(8), DIMENSION(:) :: WORK SUBROUTINE GEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO) INTEGER(8) :: M, N, LDA, LWORK, INFO REAL(8), DIMENSION(:,:) :: A REAL(8), DIMENSION(:) :: WORK C INTERFACE #include <sunperf.h> void dgeqrfp (int m, int n, double *a, int lda, double *tau, int *info); void dgeqrfp_64 (long m, long n, double *a, long lda, double *tau, long *info); PURPOSE dgeqrfp computes a QR factorization of a real M-by-N matrix A: A = Q * R. ARGUMENTS M (input) M is INTEGER The number of rows of the matrix A. M >= 0. N (input) N is INTEGER The number of columns of the matrix A. N >= 0. A (input/output) A is DOUBLE PRECISION array, dimension (LDA,N) On entry, the M-by-N matrix A. On exit, the elements on and above the diagonal of the array contain the min(M,N)-by-N upper trapezoidal matrix R (R is upper triangular if m >= n); the elements below the diagonal, with the array TAU, represent the orthogonal matrix Q as a product of min(m,n) elementary reflectors (see Further Details). LDA (input) LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M). TAU (output) TAU is DOUBLE PRECISION array, dimension (min(M,N)) The scalar factors of the elementary reflectors (see Further Details). WORK (output) WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK. LWORK (input) LWORK is INTEGER The dimension of the array WORK. LWORK >= max(1,N). For optimum performance LWORK >= N*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) INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value FURTHER DETAILS The matrix Q is represented as a product of elementary reflectors Q = H(1)*H(2) . . . H(K), where K = min(M,N). Each H(i) has the form H(i) = I - tau * v * v**T where tau is a complex scalar, and v is a complex vector with v(1:i-1) = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:M,i), and tau in TAU(i). 7 Nov 2015 dgeqrfp(3P)