Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

     cungql - generate an M-by-N complex matrix Q with  orthonor-
     mal columns,

SYNOPSIS

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

     COMPLEX A(LDA,*), TAU(*), WORK(*)
     INTEGER M, N, K, LDA, LWORK, INFO

     SUBROUTINE CUNGQL_64(M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

     COMPLEX A(LDA,*), TAU(*), WORK(*)
     INTEGER*8 M, N, K, LDA, LWORK, INFO

  F95 INTERFACE
     SUBROUTINE UNGQL(M, [N], [K], A, [LDA], TAU, [WORK], [LWORK], [INFO])

     COMPLEX, DIMENSION(:) :: TAU, WORK
     COMPLEX, DIMENSION(:,:) :: A
     INTEGER :: M, N, K, LDA, LWORK, INFO

     SUBROUTINE UNGQL_64(M, [N], [K], A, [LDA], TAU, [WORK], [LWORK],
            [INFO])

     COMPLEX, DIMENSION(:) :: TAU, WORK
     COMPLEX, DIMENSION(:,:) :: A
     INTEGER(8) :: M, N, K, LDA, LWORK, INFO

  C INTERFACE
     #include <sunperf.h>

     void cungql(int m, int n, int k, complex *a, int  lda,  com-
               plex *tau, int *info);

     void cungql_64(long m, long n, long k, complex *a, long lda,
               complex *tau, long *info);

PURPOSE

     cungql generates an M-by-N complex matrix Q with orthonormal
     columns, which is defined as the last N columns of a product
     of K elementary reflectors of order M

           Q  =  H(k) . . . H(2) H(1)

     as returned by CGEQLF.

ARGUMENTS

     M (input) The number of rows of the matrix Q. M >= 0.

     N (input) The number of columns of the matrix Q. M >=  N  >=
               0.

     K (input) The number of elementary reflectors whose  product
               defines the matrix Q. N >= K >= 0.

     A (input/output)
               On entry, the (n-k+i)-th column must  contain  the
               vector  which  defines  the  elementary  reflector
               H(i), for i = 1,2,...,k, as returned by CGEQLF  in
               the  last  k  columns of its array argument A.  On
               exit, the M-by-N matrix Q.

     LDA (input)
               The  first  dimension  of  the  array  A.  LDA  >=
               max(1,M).

     TAU (input)
               TAU(i) must contain the scalar factor of the  ele-
               mentary reflector H(i), as returned by CGEQLF.

     WORK (workspace)
               On exit, if INFO = 0, WORK(1) returns the  optimal
               LWORK.

     LWORK (input)
               The  dimension  of  the  array  WORK.   LWORK   >=
               max(1,N).   For optimum performance LWORK >= N*NB,
               where NB is the optimal 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)
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument has an ille-
               gal value