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CentOS 7.0 - man page for dla_geamv (centos section 3)

dla_geamv.f(3)				      LAPACK				   dla_geamv.f(3)

NAME
       dla_geamv.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dla_geamv (TRANS, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY)
	   DLA_GEAMV computes a matrix-vector product using a general matrix to calculate error
	   bounds.

Function/Subroutine Documentation
   subroutine dla_geamv (integerTRANS, integerM, integerN, double precisionALPHA, double
       precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )X,
       integerINCX, double precisionBETA, double precision, dimension( * )Y, integerINCY)
       DLA_GEAMV computes a matrix-vector product using a general matrix to calculate error
       bounds.

       Purpose:

	    DLA_GEAMV  performs one of the matrix-vector operations

		    y := alpha*abs(A)*abs(x) + beta*abs(y),
	       or   y := alpha*abs(A)**T*abs(x) + beta*abs(y),

	    where alpha and beta are scalars, x and y are vectors and A is an
	    m by n matrix.

	    This function is primarily used in calculating error bounds.
	    To protect against underflow during evaluation, components in
	    the resulting vector are perturbed away from zero by (N+1)
	    times the underflow threshold.  To prevent unnecessarily large
	    errors for block-structure embedded in general matrices,
	    "symbolically" zero components are not perturbed.  A zero
	    entry is considered "symbolic" if all multiplications involved
	    in computing that entry have at least one zero multiplicand.

       Parameters:
	   TRANS

		     TRANS is INTEGER
		      On entry, TRANS specifies the operation to be performed as
		      follows:

			BLAS_NO_TRANS	   y := alpha*abs(A)*abs(x) + beta*abs(y)
			BLAS_TRANS	   y := alpha*abs(A**T)*abs(x) + beta*abs(y)
			BLAS_CONJ_TRANS    y := alpha*abs(A**T)*abs(x) + beta*abs(y)

		      Unchanged on exit.

	   M

		     M is INTEGER
		      On entry, M specifies the number of rows of the matrix A.
		      M must be at least zero.
		      Unchanged on exit.

	   N

		     N is INTEGER
		      On entry, N specifies the number of columns of the matrix A.
		      N must be at least zero.
		      Unchanged on exit.

	   ALPHA

		     ALPHA is DOUBLE PRECISION
		      On entry, ALPHA specifies the scalar alpha.
		      Unchanged on exit.

	   A

		     A is DOUBLE PRECISION array of DIMENSION ( LDA, n )
		      Before entry, the leading m by n part of the array A must
		      contain the matrix of coefficients.
		      Unchanged on exit.

	   LDA

		     LDA is 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.

	   X

		     X is DOUBLE PRECISION array, dimension
		      ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'
		      and at least
		      ( 1 + ( m - 1 )*abs( INCX ) ) otherwise.
		      Before entry, the incremented array X must contain the
		      vector x.
		      Unchanged on exit.

	   INCX

		     INCX is INTEGER
		      On entry, INCX specifies the increment for the elements of
		      X. INCX must not be zero.
		      Unchanged on exit.

	   BETA

		     BETA is DOUBLE PRECISION
		      On entry, BETA specifies the scalar beta. When BETA is
		      supplied as zero then Y need not be set on input.
		      Unchanged on exit.

	   Y

		     Y is DOUBLE PRECISION
		      Array of DIMENSION at least
		      ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'
		      and at least
		      ( 1 + ( n - 1 )*abs( INCY ) ) otherwise.
		      Before entry with BETA non-zero, the incremented array Y
		      must contain the vector y. On exit, Y is overwritten by the
		      updated vector y.

	   INCY

		     INCY is INTEGER
		      On entry, INCY specifies the increment for the elements of
		      Y. INCY must not be zero.
		      Unchanged on exit.

	     Level 2 Blas routine.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Definition at line 174 of file dla_geamv.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			   dla_geamv.f(3)


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