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 gen­
       eral 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 gen­
       eral 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 eigen­
       vectors  of  the generalized symmetric definite eigenprob­
       lem.


ARGUMENTS

       JOB     (input) CHARACTER*1
               Specifies for which problem the reciprocal  condi­
               tion 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 =


       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 ille­
               gal value.


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