sdisna(l) [redhat man page]

SDISNA(l)								 )								 SDISNA(l)

NAME

       SDISNA  -  compute the reciprocal condition numbers for the eigenvectors of a real symmetric or complex Hermitian matrix or for the left or
       right singular vectors of a general m-by-n matrix

SYNOPSIS

       SUBROUTINE SDISNA( JOB, M, N, D, SEP, INFO )

	   CHARACTER	  JOB

	   INTEGER	  INFO, M, N

	   REAL 	  D( * ), SEP( * )

PURPOSE

       SDISNA computes the reciprocal condition numbers for the eigenvectors of a real symmetric or complex Hermitian matrix or for  the  left	or
       right  singular	vectors  of  a general m-by-n matrix. The reciprocal condition number is the 'gap' between the corresponding eigenvalue or
       singular value and the nearest other one.

       The bound on the error, measured by angle in radians, in the I-th computed vector is given by

	      SLAMCH( 'E' ) * ( ANORM / SEP( I ) )

       where ANORM = 2-norm(A) = max( abs( D(j) ) ).  SEP(I) is not allowed to be smaller than SLAMCH( 'E' )*ANORM in order to limit the  size	of
       the error bound.

       SDISNA may also be used to compute error bounds for eigenvectors of the generalized symmetric definite eigenproblem.

ARGUMENTS

       JOB     (input) CHARACTER*1
	       Specifies for which problem the reciprocal condition numbers should be computed:
	       = 'E':  the eigenvectors of a symmetric/Hermitian matrix;
	       = 'L':  the left singular vectors of a general matrix;
	       = 'R':  the right singular vectors of a general matrix.

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

       N       (input) INTEGER
	       If JOB = 'L' or 'R', the number of columns of the matrix, in which case N >= 0. Ignored if JOB = 'E'.

       D       (input) REAL array, dimension (M) if JOB = 'E'
	       dimension  (min(M,N))  if  JOB  = 'L' or 'R' The eigenvalues (if JOB = 'E') or singular values (if JOB = order. If singular values,
	       they must be non-negative.

       SEP     (output) REAL array, dimension (M) if JOB = 'E'
	       dimension (min(M,N)) if JOB = 'L' or 'R' The reciprocal condition numbers of the vectors.

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

LAPACK version 3.0						   15 June 2000 							 SDISNA(l)

ddisna.f(3)							      LAPACK							       ddisna.f(3)

NAME

       ddisna.f -

SYNOPSIS

   Functions/Subroutines
       subroutine ddisna (JOB, M, N, D, SEP, INFO)
	   DDISNA

Function/Subroutine Documentation
   subroutine ddisna (characterJOB, integerM, integerN, double precision, dimension( * )D, double precision, dimension( * )SEP, integerINFO)
       DDISNA

       Purpose:

	    DDISNA computes the reciprocal condition numbers for the eigenvectors
	    of a real symmetric or complex Hermitian matrix or for the left or
	    right singular vectors of a general m-by-n matrix. The reciprocal
	    condition number is the 'gap' between the corresponding eigenvalue or
	    singular value and the nearest other one.

	    The bound on the error, measured by angle in radians, in the I-th
	    computed vector is given by

		   DLAMCH( 'E' ) * ( ANORM / SEP( I ) )

	    where ANORM = 2-norm(A) = max( abs( D(j) ) ).  SEP(I) is not allowed
	    to be smaller than DLAMCH( 'E' )*ANORM in order to limit the size of
	    the error bound.

	    DDISNA may also be used to compute error bounds for eigenvectors of
	    the generalized symmetric definite eigenproblem.

       Parameters:
	   JOB

		     JOB is CHARACTER*1
		     Specifies for which problem the reciprocal condition numbers
		     should be computed:
		     = 'E':  the eigenvectors of a symmetric/Hermitian matrix;
		     = 'L':  the left singular vectors of a general matrix;
		     = 'R':  the right singular vectors of a general matrix.

	   M

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

	   N

		     N is INTEGER
		     If JOB = 'L' or 'R', the number of columns of the matrix,
		     in which case N >= 0. Ignored if JOB = 'E'.

	   D

		     D is DOUBLE PRECISION array, dimension (M) if JOB = 'E'
					 dimension (min(M,N)) if JOB = 'L' or 'R'
		     The eigenvalues (if JOB = 'E') or singular values (if JOB =
		     'L' or 'R') of the matrix, in either increasing or decreasing
		     order. If singular values, they must be non-negative.

	   SEP

		     SEP is DOUBLE PRECISION array, dimension (M) if JOB = 'E'
					  dimension (min(M,N)) if JOB = 'L' or 'R'
		     The reciprocal condition numbers of the vectors.

	   INFO

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

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 118 of file ddisna.f.

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

Version 3.4.1							  Sun May 26 2013						       ddisna.f(3)