SRC/cung2l.f(3)

NAME
SRC/cung2l.f

SYNOPSIS

  Functions/Subroutines
subroutine cung2l (m, n, k, a, lda, tau, work, info)
CUNG2L generates all or part of the unitary matrix Q from a QL factorization determined by cgeqlf (unblocked algorithm).

Function/Subroutine Documentation

  subroutine cung2l (integer m, integer n, integer k, complex, dimension( lda, * ) a, integer lda, complex, dimension( * ) tau, complex, dimension( * ) work, integer info)

CUNG2L generates all or part of the unitary matrix Q from a QL factorization determined by cgeqlf (unblocked algorithm).

Purpose:

     CUNG2L 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.

Parameters
    M

              M is INTEGER
              The number of rows of the matrix Q. M >= 0.

    N

              N is INTEGER
              The number of columns of the matrix Q. M >= N >= 0.

    K

              K is INTEGER
              The number of elementary reflectors whose product defines the
              matrix Q. N >= K >= 0.

    A

              A is COMPLEX array, dimension (LDA,N)
              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

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

    TAU

              TAU is COMPLEX array, dimension (K)
              TAU(i) must contain the scalar factor of the elementary
              reflector H(i), as returned by CGEQLF.

    WORK

              WORK is COMPLEX array, dimension (N)

    INFO

              INFO is INTEGER
              = 0: successful exit
              < 0: if INFO = -i, the i-th argument has an illegal value

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 113 of file cung2l.f.

Author

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