.TH "SRC/ddisna.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/ddisna.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBddisna\fP (job, m, n, d, sep, info)"
.br
.RI "\fBDDISNA\fP "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine ddisna (character job, integer m, integer n, double precision, dimension( * ) d, double precision, dimension( * ) sep, integer info)"

.PP
\fBDDISNA\fP  
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\fBPurpose:\fP
.RS 4

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.nf
!>
!> 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\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIJOB\fP 
.PP
.nf
!>          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\&.
!> 
.fi
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.br
\fIM\fP 
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!>          M is INTEGER
!>          The number of rows of the matrix\&. M >= 0\&.
!> 
.fi
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\fIN\fP 
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!>          N is INTEGER
!>          If JOB = 'L' or 'R', the number of columns of the matrix,
!>          in which case N >= 0\&. Ignored if JOB = 'E'\&.
!> 
.fi
.PP
.br
\fID\fP 
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.nf
!>          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\&.
!> 
.fi
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.br
\fISEP\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fIINFO\fP 
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.nf
!>          INFO is INTEGER
!>          = 0:  successful exit\&.
!>          < 0:  if INFO = -i, the i-th argument had an illegal value\&.
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

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Univ\&. of California Berkeley 

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Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 
.RE
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Definition at line \fB116\fP of file \fBddisna\&.f\fP\&.
.SH "Author"
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Generated automatically by Doxygen for LAPACK from the source code\&.