Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?sysvx

Uses the diagonal pivoting factorization to compute the solution to the system of linear equations with a real or complex symmetric coefficient matrix A, and provides error bounds on the solution.

Syntax

call ssysvx
(
fact
,
uplo
,
n
,
nrhs
,
a
,
lda
,
af
,
ldaf
,
ipiv
,
b
,
ldb
,
x
,
ldx
,
rcond
,
ferr
,
berr
,
work
,
lwork
,
iwork
,
info
)
call dsysvx
(
fact
,
uplo
,
n
,
nrhs
,
a
,
lda
,
af
,
ldaf
,
ipiv
,
b
,
ldb
,
x
,
ldx
,
rcond
,
ferr
,
berr
,
work
,
lwork
,
iwork
,
info
)
call csysvx
(
fact
,
uplo
,
n
,
nrhs
,
a
,
lda
,
af
,
ldaf
,
ipiv
,
b
,
ldb
,
x
,
ldx
,
rcond
,
ferr
,
berr
,
work
,
lwork
,
rwork
,
info
)
call zsysvx
(
fact
,
uplo
,
n
,
nrhs
,
a
,
lda
,
af
,
ldaf
,
ipiv
,
b
,
ldb
,
x
,
ldx
,
rcond
,
ferr
,
berr
,
work
,
lwork
,
rwork
,
info
)
call sysvx
(
a
,
b
,
x
[
,
uplo
]
[
,
af
]
[
,
ipiv
]
[
,
fact
]
[
,
ferr
]
[
,
berr
]
[
,
rcond
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine uses the diagonal pivoting factorization to compute the solution to a real or complex system of linear equations
A*X
=
B
, where
A
is a
n
-by-
n
symmetric matrix, the columns of matrix
B
are individual right-hand sides, and the columns of
X
are the corresponding solutions.
Error bounds on the solution and a condition estimate are also provided.
The routine
?sysvx
performs the following steps:
  1. If
    fact
    =
    'N'
    , the diagonal pivoting method is used to factor the matrix
    A
    . The form of the factorization is
    A
    =
    U*D*U
    T
    or
    A
    =
    L*D*L
    T
    , where
    U
    (or
    L
    ) is a product of permutation and unit upper (lower) triangular matrices, and
    D
    is symmetric and block diagonal with 1-by-1 and 2-by-2 diagonal blocks.