table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sdisna.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sdisna.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sdisna.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine SDISNA (job, m, n, d, sep, info)
SDISNA
Function/Subroutine Documentation¶
subroutine SDISNA (character job, integer m, integer n, real, dimension( * ) d, real, dimension( * ) sep, integer info)¶
SDISNA
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. !>
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 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 = !> 'L' or 'R') of the matrix, in either increasing or decreasing !> order. If singular values, they must be non-negative. !>
SEP
!> SEP is REAL 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.
Definition at line 116 of file sdisna.f.
Author¶
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Version 3.12.0 | LAPACK |