zunml2(3S)

NAME
     ZUNML2 - overwrite the general complex m-by-n matrix C with  Q * C if
     SIDE = 'L' and TRANS = 'N', or  Q'* C if SIDE = 'L' and TRANS = 'C', or
     C * Q if SIDE = 'R' and TRANS = 'N', or  C * Q' if SIDE = 'R' and TRANS =
     'C',

SYNOPSIS
     SUBROUTINE ZUNML2( SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, INFO
                        )

         CHARACTER      SIDE, TRANS

         INTEGER        INFO, K, LDA, LDC, M, N

         COMPLEX*16     A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

PURPOSE
     ZUNML2 overwrites the general complex m-by-n matrix C with Q * C if SIDE
     = 'L' and TRANS = 'N', or Q'* C if SIDE = 'L' and TRANS = 'C', or C * Q
     if SIDE = 'R' and TRANS = 'N', or C * Q' if SIDE = 'R' and TRANS = 'C',
     where Q is a complex unitary matrix defined as the product of k
     elementary reflectors

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

     as returned by ZGELQF. Q is of order m if SIDE = 'L' and of order n if
     SIDE = 'R'.


ARGUMENTS
     SIDE    (input) CHARACTER*1
             = 'L': apply Q or Q' from the Left
             = 'R': apply Q or Q' from the Right

     TRANS   (input) CHARACTER*1
             = 'N': apply Q  (No transpose)
             = 'C': apply Q' (Conjugate transpose)
     M       (input) INTEGER
             The number of rows of the matrix C. M >= 0.

     N       (input) INTEGER
             The number of columns of the matrix C. N >= 0.

     K       (input) INTEGER
             The number of elementary reflectors whose product defines the
             matrix Q.  If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >=
             0.

     A       (input) COMPLEX*16 array, dimension
             (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' The i-th row must
             contain the vector which defines the elementary reflector H(i),
             for i = 1,2,...,k, as returned by ZGELQF in the first k rows of
             its array argument A.  A is modified by the routine but restored
             on exit.

     LDA     (input) INTEGER
             The leading dimension of the array A. LDA >= max(1,K).

     TAU     (input) COMPLEX*16 array, dimension (K)
             TAU(i) must contain the scalar factor of the elementary reflector
             H(i), as returned by ZGELQF.

     C       (input/output) COMPLEX*16 array, dimension (LDC,N)
             On entry, the m-by-n matrix C.  On exit, C is overwritten by Q*C
             or Q'*C or C*Q' or C*Q.

     LDC     (input) INTEGER
             The leading dimension of the array C. LDC >= max(1,M).

     WORK    (workspace) COMPLEX*16 array, dimension
             (N) if SIDE = 'L', (M) if SIDE = 'R'

     INFO    (output) INTEGER
             = 0: successful exit
             < 0: if INFO = -i, the i-th argument had an illegal value

SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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