sgerq2 (3p)

Name

sgerq2 - computes the RQ factorization of a general rectangular matrix using an unblocked algorithm

Synopsis

SUBROUTINE SGERQ2(M, N, A, LDA, TAU, WORK, INFO)


INTEGER INFO, LDA, M, N

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


SUBROUTINE SGERQ2_64(M, N, A, LDA, TAU, WORK, INFO)


INTEGER*8 INFO, LDA, M, N

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


F95 INTERFACE
SUBROUTINE GERQ2(M, N, A, LDA, TAU, WORK, INFO)


REAL, DIMENSION(:,:) :: A

INTEGER :: M, N, LDA, INFO

REAL, DIMENSION(:) :: TAU, WORK


SUBROUTINE GERQ2_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 sgerq2 (int m, int n, float *a, int lda, float *tau, int *info);


void sgerq2_64 (long m, long n, float *a, long lda,  float  *tau,  long
*info);

Description

Oracle Solaris Studio Performance Library                           sgerq2(3P)



NAME
       sgerq2  - computes the RQ factorization of a general rectangular matrix
       using an unblocked algorithm


SYNOPSIS
       SUBROUTINE SGERQ2(M, N, A, LDA, TAU, WORK, INFO)


       INTEGER INFO, LDA, M, N

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


       SUBROUTINE SGERQ2_64(M, N, A, LDA, TAU, WORK, INFO)


       INTEGER*8 INFO, LDA, M, N

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


   F95 INTERFACE
       SUBROUTINE GERQ2(M, N, A, LDA, TAU, WORK, INFO)


       REAL, DIMENSION(:,:) :: A

       INTEGER :: M, N, LDA, INFO

       REAL, DIMENSION(:) :: TAU, WORK


       SUBROUTINE GERQ2_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 sgerq2 (int m, int n, float *a, int lda, float *tau, int *info);


       void sgerq2_64 (long m, long n, float *a, long lda,  float  *tau,  long
                 *info);


PURPOSE
       sgerq2  computes an RQ factorization of a real m by n matrix A: A = R *
       Q.


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, 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 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 (M)


       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 real scalar, and v is a real vector with
       v(n-k+i+1:n) = 0 and v(n-k+i) = 1; v(1:n-k+i-1) is stored on exit in
       A(m-k+i,1:n-k+i-1), and tau in TAU(i).



                                  7 Nov 2015                        sgerq2(3P)