dspcon (l) - Linux Manuals
dspcon: estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric packed matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF
Command to display dspcon
manual in Linux: $ man l dspcon
NAME
DSPCON - estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric packed matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF
SYNOPSIS
- SUBROUTINE DSPCON(
-
UPLO, N, AP, IPIV, ANORM, RCOND, WORK, IWORK,
INFO )
-
CHARACTER
UPLO
-
INTEGER
INFO, N
-
DOUBLE
PRECISION ANORM, RCOND
-
INTEGER
IPIV( * ), IWORK( * )
-
DOUBLE
PRECISION AP( * ), WORK( * )
PURPOSE
DSPCON estimates the reciprocal of the condition number (in the
1-norm) of a real symmetric packed matrix A using the factorization
A = U*D*U**T or A = L*D*L**T computed by DSPTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
ARGUMENTS
- UPLO (input) CHARACTER*1
-
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix.
= aqUaq: Upper triangular, form is A = U*D*U**T;
= aqLaq: Lower triangular, form is A = L*D*L**T.
- N (input) INTEGER
-
The order of the matrix A. N >= 0.
- AP (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
-
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by DSPTRF, stored as a
packed triangular matrix.
- IPIV (input) INTEGER array, dimension (N)
-
Details of the interchanges and the block structure of D
as determined by DSPTRF.
- ANORM (input) DOUBLE PRECISION
-
The 1-norm of the original matrix A.
- RCOND (output) DOUBLE PRECISION
-
The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
estimate of the 1-norm of inv(A) computed in this routine.
- WORK (workspace) DOUBLE PRECISION array, dimension (2*N)
-
- IWORK (workspace) INTEGER array, dimension (N)
-
- INFO (output) INTEGER
-
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
Pages related to dspcon
- dspcon (3)
- dspev (l) - computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage
- dspevd (l) - computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage
- dspevx (l) - computes selected eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage
- dspgst (l) - reduces a real symmetric-definite generalized eigenproblem to standard form, using packed storage
- dspgv (l) - computes all the eigenvalues and, optionally, the eigenvectors of a real generalized symmetric-definite eigenproblem, of the form A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x
- dspgvd (l) - computes all the eigenvalues, and optionally, the eigenvectors of a real generalized symmetric-definite eigenproblem, of the form A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x
- dspgvx (l) - computes selected eigenvalues, and optionally, eigenvectors of a real generalized symmetric-definite eigenproblem, of the form A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x