cgeqr2p (3p)

Name

cgeqr2p - computes the QR factorization of a general rectangular matrix with non-negative diagonal elements using an unblocked algorithm.

Synopsis

SUBROUTINE CGEQR2P(M, N, A, LDA, TAU, WORK, INFO)


INTEGER INFO, LDA, M, N

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


SUBROUTINE CGEQR2P_64(M, N, A, LDA, TAU, WORK, INFO)


INTEGER*8 INFO, LDA, M, N

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


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


INTEGER :: M, N, LDA, INFO

COMPLEX, DIMENSION(:) :: TAU, WORK

COMPLEX, DIMENSION(:,:) :: A


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


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

COMPLEX, DIMENSION(:) :: TAU, WORK

COMPLEX, DIMENSION(:,:) :: A


C INTERFACE
#include <sunperf.h>

void cgeqr2p (int m, int n,  floatcomplex  *a,  int  lda,  floatcomplex
*tau, int *info);


void  cgeqr2p_64  (long m, long n, floatcomplex *a, long lda, floatcom-
plex *tau, long *info);

Description

Oracle Solaris Studio Performance Library                          cgeqr2p(3P)



NAME
       cgeqr2p - computes the QR factorization of a general rectangular matrix
       with non-negative diagonal elements using an unblocked algorithm.


SYNOPSIS
       SUBROUTINE CGEQR2P(M, N, A, LDA, TAU, WORK, INFO)


       INTEGER INFO, LDA, M, N

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


       SUBROUTINE CGEQR2P_64(M, N, A, LDA, TAU, WORK, INFO)


       INTEGER*8 INFO, LDA, M, N

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


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


       INTEGER :: M, N, LDA, INFO

       COMPLEX, DIMENSION(:) :: TAU, WORK

       COMPLEX, DIMENSION(:,:) :: A


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


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

       COMPLEX, DIMENSION(:) :: TAU, WORK

       COMPLEX, DIMENSION(:,:) :: A


   C INTERFACE
       #include <sunperf.h>

       void cgeqr2p (int m, int n,  floatcomplex  *a,  int  lda,  floatcomplex
                 *tau, int *info);


       void  cgeqr2p_64  (long m, long n, floatcomplex *a, long lda, floatcom-
                 plex *tau, long *info);


PURPOSE
       cgeqr2p computes a QR factorization of a  complex  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 COMPLEX 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 unitary matrix Q as a prod-
                 uct 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 COMPLEX array, dimension (min(M,N))
                 The  scalar factors of the elementary reflectors (see Further
                 Details).


       WORK (output)
                 WORK is COMPLEX 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**H
       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                       cgeqr2p(3P)