CSIFA(3F)CSIFA(3F)NAMECSIFA - CSIFA factors a complex symmetric matrix by elimination with
symmetric pivoting.
To solve A*X = B , follow CSIFA by CSISL. To compute INVERSE(A)*C ,
follow CSIFA by CSISL. To compute DETERMINANT(A) , follow CSIFA by
CSIDI. To compute INVERSE(A) , follow CSIFA by CSIDI.
SYNOPSYS
SUBROUTINE CSIFA(A,LDA,N,KPVT,INFO)
DESCRIPTION
On Entry
A COMPLEX(LDA,N)
the symmetric matrix to be factored.
Only the diagonal and upper triangle are used.
LDA INTEGER
the leading dimension of the array A .
N INTEGER
the order of the matrix A . On Return
A a block diagonal matrix and the multipliers which
were used to obtain it.
The factorization can be written A = U*D*TRANS(U)
where U is a product of permutation and unit
upper triangular matrices , TRANS(U) is the
transpose of U , and D is block diagonal
with 1 by 1 and 2 by 2 blocks. KVPT INTEGER(N)
an integer vector of pivot indices.
INFO INTEGER
= 0 normal value.
= K if the K-th pivot block is singular. This is
not an error condition for this subroutine,
but it does indicate that CSISL or CSIDI may
divide by zero if called. LINPACK. This version dated 08/14/78 .
James Bunch, Univ. Calif. San Diego, Argonne Nat. Lab. Subroutines and
Functions BLAS CAXPY,CSWAP,ICAMAX Fortran ABS,AIMAG,AMAX1,REAL,SQRT
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