sgeqr2p (3p)

Name

sgeqr2p - computes the QR factorization of a general rectangular matrix with non-negative diagonal elements using an unblocked algorithm.

Synopsis

SUBROUTINE SGEQR2P(M, N, A, LDA, TAU, WORK, INFO)


INTEGER INFO, LDA, M, N

REAL A(LDA,*), TAU(*), WORK(*)


SUBROUTINE SGEQR2P_64(M, N, A, LDA, TAU, WORK, INFO)


INTEGER*8 INFO, LDA, M, N

REAL A(LDA,*), TAU(*), WORK(*)


F95 INTERFACE
SUBROUTINE GEQR2P(M, N, A, LDA, TAU, WORK, INFO )


REAL, DIMENSION(:,:) :: A

INTEGER :: M, N, LDA, INFO

REAL, DIMENSION(:) :: TAU, WORK


SUBROUTINE GEQR2P_64(M, N, A, LDA, TAU, WORK, INFO)


REAL, DIMENSION(:,:) :: A

INTEGER(8) :: M, N, LDA, INFO

REAL, DIMENSION(:) :: TAU, WORK


C INTERFACE
#include <sunperf.h>

void sgeqr2p (int m, int n, float *a, int lda, float *tau, int *info);


void sgeqr2p_64 (long m, long n, float *a, long lda, float  *tau,  long
*info);

Description

Oracle Solaris Studio Performance Library                          sgeqr2p(3P)



NAME
       sgeqr2p - computes the QR factorization of a general rectangular matrix
       with non-negative diagonal elements using an unblocked algorithm.


SYNOPSIS
       SUBROUTINE SGEQR2P(M, N, A, LDA, TAU, WORK, INFO)


       INTEGER INFO, LDA, M, N

       REAL A(LDA,*), TAU(*), WORK(*)


       SUBROUTINE SGEQR2P_64(M, N, A, LDA, TAU, WORK, INFO)


       INTEGER*8 INFO, LDA, M, N

       REAL A(LDA,*), TAU(*), WORK(*)


   F95 INTERFACE
       SUBROUTINE GEQR2P(M, N, A, LDA, TAU, WORK, INFO )


       REAL, DIMENSION(:,:) :: A

       INTEGER :: M, N, LDA, INFO

       REAL, DIMENSION(:) :: TAU, WORK


       SUBROUTINE GEQR2P_64(M, N, A, LDA, TAU, WORK, INFO)


       REAL, DIMENSION(:,:) :: A

       INTEGER(8) :: M, N, LDA, INFO

       REAL, DIMENSION(:) :: TAU, WORK


   C INTERFACE
       #include <sunperf.h>

       void sgeqr2p (int m, int n, float *a, int lda, float *tau, int *info);


       void sgeqr2p_64 (long m, long n, float *a, long lda, float  *tau,  long
                 *info);


PURPOSE
       sgeqr2p 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 REAL 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 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 REAL array, dimension (min(M,N))
                 The  scalar factors of the elementary reflectors (see Further
                 Details).


       WORK (output)
                 WORK is REAL array, dimension (N)


       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                       sgeqr2p(3P)