Source module last modified on Thu, 2 Jul 1998, 23:17;
HTML image of Fortran source automatically generated by
for2html on Sun, 23 Jun 2002, 15:10.
SUBROUTINE CGERC ( M, N, ALPHA, X, INCX, Y, INCY, A, LDA )
# .. Scalar Arguments ..
COMPLEX ALPHA
INTEGER INCX, INCY, LDA, M, N
# .. Array Arguments ..
COMPLEX A( LDA, * ), X( * ), Y( * )
# ..
#
# Purpose
# =======
#
# CGERC performs the rank 1 operation
#
# A := alpha*x*conjg( y' ) + A,
#
# where alpha is a scalar, x is an m element vector, y is an n element
# vector and A is an m by n matrix.
#
# Parameters
# ==========
#
# M - INTEGER.
# On entry, M specifies the number of rows of the matrix A.
# M must be at least zero.
# Unchanged on exit.
#
# N - INTEGER.
# On entry, N specifies the number of columns of the matrix A.
# N must be at least zero.
# Unchanged on exit.
#
# ALPHA - COMPLEX .
# On entry, ALPHA specifies the scalar alpha.
# Unchanged on exit.
#
# X - COMPLEX array of dimension at least
# ( 1 + ( m - 1 )*abs( INCX ) ).
# Before entry, the incremented array X must contain the m
# element vector x.
# Unchanged on exit.
#
# INCX - INTEGER.
# On entry, INCX specifies the increment for the elements of
# X. INCX must not be zero.
# Unchanged on exit.
#
# Y - COMPLEX array of dimension at least
# ( 1 + ( n - 1 )*abs( INCY ) ).
# Before entry, the incremented array Y must contain the n
# element vector y.
# Unchanged on exit.
#
# INCY - INTEGER.
# On entry, INCY specifies the increment for the elements of
# Y. INCY must not be zero.
# Unchanged on exit.
#
# A - COMPLEX array of DIMENSION ( LDA, n ).
# Before entry, the leading m by n part of the array A must
# contain the matrix of coefficients. On exit, A is
# overwritten by the updated matrix.
#
# LDA - INTEGER.
# On entry, LDA specifies the first dimension of A as declared
# in the calling (sub) program. LDA must be at least
# max( 1, m ).
# Unchanged on exit.
#
#
# Level 2 Blas routine.
#
# -- Written on 22-October-1986.
# Jack Dongarra, Argonne National Lab.
# Jeremy Du Croz, Nag Central Office.
# Sven Hammarling, Nag Central Office.
# Richard Hanson, Sandia National Labs.
#
#
# .. Parameters ..
COMPLEX ZERO
PARAMETER ( ZERO = ( 0.0E+0, 0.0E+0 ) )
# .. Local Scalars ..
COMPLEX TEMP
INTEGER I, INFO, IX, J, JY, KX
# .. External Subroutines ..
EXTERNAL XERBLA
# .. Intrinsic Functions ..
INTRINSIC CONJG, MAX
# ..
# .. Executable Statements ..
#
# Test the input parameters.
#
INFO = 0
IF ( M<0 )THEN
INFO = 1
ELSE IF( N<0 )THEN
INFO = 2
ELSE IF( INCX==0 )THEN
INFO = 5
ELSE IF( INCY==0 )THEN
INFO = 7
ELSE IF( LDA<MAX( 1, M ) )THEN
INFO = 9
END IF
IF( INFO!=0 )THEN
CALL XERBLA( 'CGERC ', INFO )
RETURN
END IF
#
# Quick return if possible.
#
IF( ( M==0 )||( N==0 )||( ALPHA==ZERO ) )
$ RETURN
#
# Start the operations. In this version the elements of A are
# accessed sequentially with one pass through A.
#
IF( INCY>0 )THEN
JY = 1
ELSE
JY = 1 - ( N - 1 )*INCY
END IF
IF( INCX==1 )THEN
DO 20, J = 1, N
IF( Y( JY )!=ZERO )THEN
TEMP = ALPHA*CONJG( Y( JY ) )
DO 10, I = 1, M
A( I, J ) = A( I, J ) + X( I )*TEMP
10 CONTINUE
END IF
JY = JY + INCY
20 CONTINUE
ELSE
IF( INCX>0 )THEN
KX = 1
ELSE
KX = 1 - ( M - 1 )*INCX
END IF
DO 40, J = 1, N
IF( Y( JY )!=ZERO )THEN
TEMP = ALPHA*CONJG( Y( JY ) )
IX = KX
DO 30, I = 1, M
A( I, J ) = A( I, J ) + X( IX )*TEMP
IX = IX + INCX
30 CONTINUE
END IF
JY = JY + INCY
40 CONTINUE
END IF
#
RETURN
#
# End of CGERC .
#
END