cgeqrfp (3p)

Name

cgeqrfp - N matrix A: A = Q * R

Synopsis

SUBROUTINE CGEQRFP(M, N, A, LDA, TAU, WORK, LWORK, INFO)


INTEGER INFO, LDA, LWORK, M, N

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


SUBROUTINE CGEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO)


INTEGER*8 INFO, LDA, LWORK, M, N

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


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


INTEGER :: M, N, LDA, LWORK, INFO

COMPLEX, DIMENSION(:,:) :: A

COMPLEX, DIMENSION(:) :: TAU, WORK


SUBROUTINE GEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO)


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

COMPLEX, DIMENSION(:,:) :: A

COMPLEX, DIMENSION(:) :: TAU, WORK


C INTERFACE
#include <sunperf.h>

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


void  cgeqrfp_64  (long m, long n, floatcomplex *a, long lda, floatcom-
plex *tau, long *info);

Description

Oracle Solaris Studio Performance Library                          cgeqrfp(3P)



NAME
       cgeqrfp  - compute a QR factorization of a complex M-by-N matrix A: A =
       Q * R


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


       INTEGER INFO, LDA, LWORK, M, N

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


       SUBROUTINE CGEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO)


       INTEGER*8 INFO, LDA, LWORK, M, N

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


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


       INTEGER :: M, N, LDA, LWORK, INFO

       COMPLEX, DIMENSION(:,:) :: A

       COMPLEX, DIMENSION(:) :: TAU, WORK


       SUBROUTINE GEQRFP_64(M, N, A, LDA, TAU, WORK, LWORK, INFO)


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

       COMPLEX, DIMENSION(:,:) :: A

       COMPLEX, DIMENSION(:) :: TAU, WORK


   C INTERFACE
       #include <sunperf.h>

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


       void  cgeqrfp_64  (long m, long n, floatcomplex *a, long lda, floatcom-
                 plex *tau, long *info);


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


       WORK (output)
                 WORK is COMPLEX 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**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                       cgeqrfp(3P)