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LAPACK
3.4.0
LAPACK: Linear Algebra PACKage
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LAPACK
3.4.0
LAPACK: Linear Algebra PACKage
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Go to the source code of this file.
Functions/Subroutines | |
| subroutine | CHERFS (UPLO, N, NRHS, A, LDA, AF, LDAF, IPIV, B, LDB, X, LDX, FERR, BERR, WORK, RWORK, INFO) |
| CHERFS | |
| subroutine CHERFS | ( | CHARACTER | UPLO, |
| INTEGER | N, | ||
| INTEGER | NRHS, | ||
| COMPLEX, dimension( lda, * ) | A, | ||
| INTEGER | LDA, | ||
| COMPLEX, dimension( ldaf, * ) | AF, | ||
| INTEGER | LDAF, | ||
| INTEGER, dimension( * ) | IPIV, | ||
| COMPLEX, dimension( ldb, * ) | B, | ||
| INTEGER | LDB, | ||
| COMPLEX, dimension( ldx, * ) | X, | ||
| INTEGER | LDX, | ||
| REAL, dimension( * ) | FERR, | ||
| REAL, dimension( * ) | BERR, | ||
| COMPLEX, dimension( * ) | WORK, | ||
| REAL, dimension( * ) | RWORK, | ||
| INTEGER | INFO | ||
| ) |
CHERFS
Download CHERFS + dependencies [TGZ] [ZIP] [TXT]CHERFS improves the computed solution to a system of linear equations when the coefficient matrix is Hermitian indefinite, and provides error bounds and backward error estimates for the solution.
| [in] | UPLO |
UPLO is CHARACTER*1
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
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| [in] | N |
N is INTEGER
The order of the matrix A. N >= 0.
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| [in] | NRHS |
NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices B and X. NRHS >= 0.
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| [in] | A |
A is COMPLEX array, dimension (LDA,N)
The Hermitian matrix A. If UPLO = 'U', the leading N-by-N
upper triangular part of A contains the upper triangular part
of the matrix A, and the strictly lower triangular part of A
is not referenced. If UPLO = 'L', the leading N-by-N lower
triangular part of A contains the lower triangular part of
the matrix A, and the strictly upper triangular part of A is
not referenced.
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| [in] | LDA |
LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,N).
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| [in] | AF |
AF is COMPLEX array, dimension (LDAF,N)
The factored form of the matrix A. AF contains the block
diagonal matrix D and the multipliers used to obtain the
factor U or L from the factorization A = U*D*U**H or
A = L*D*L**H as computed by CHETRF.
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| [in] | LDAF |
LDAF is INTEGER
The leading dimension of the array AF. LDAF >= max(1,N).
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| [in] | IPIV |
IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by CHETRF.
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| [in] | B |
B is COMPLEX array, dimension (LDB,NRHS)
The right hand side matrix B.
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| [in] | LDB |
LDB is INTEGER
The leading dimension of the array B. LDB >= max(1,N).
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| [in,out] | X |
X is COMPLEX array, dimension (LDX,NRHS)
On entry, the solution matrix X, as computed by CHETRS.
On exit, the improved solution matrix X.
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| [in] | LDX |
LDX is INTEGER
The leading dimension of the array X. LDX >= max(1,N).
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| [out] | FERR |
FERR is REAL array, dimension (NRHS)
The estimated forward error bound for each solution vector
X(j) (the j-th column of the solution matrix X).
If XTRUE is the true solution corresponding to X(j), FERR(j)
is an estimated upper bound for the magnitude of the largest
element in (X(j) - XTRUE) divided by the magnitude of the
largest element in X(j). The estimate is as reliable as
the estimate for RCOND, and is almost always a slight
overestimate of the true error.
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| [out] | BERR |
BERR is REAL array, dimension (NRHS)
The componentwise relative backward error of each solution
vector X(j) (i.e., the smallest relative change in
any element of A or B that makes X(j) an exact solution).
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| [out] | WORK |
WORK is COMPLEX array, dimension (2*N)
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| [out] | RWORK |
RWORK is REAL array, dimension (N)
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| [out] | INFO |
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
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ITMAX is the maximum number of steps of iterative refinement.
Definition at line 192 of file cherfs.f.
1.7.6.1 
