CHIFA(3F) CHIFA(3F)
CHIFA  CHIFA factors a complex Hermitian matrix by elimination with
symmetric pivoting.
To solve A*X = B , follow CHIFA by CHISL. To compute INVERSE(A)*C ,
follow CHIFA by CHISL. To compute DETERMINANT(A) , follow CHIFA by
CHIDI. To compute INERTIA(A) , follow CHIFA by CHIDI. To compute
INVERSE(A) , follow CHIFA by CHIDI.
SUBROUTINE CHIFA(A,LDA,N,KPVT,INFO)
On Entry
A COMPLEX(LDA,N)
the Hermitian 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*CTRANS(U)
where U is a product of permutation and unit
upper triangular matrices , CTRANS(U) is the
conjugate 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 Kth pivot block is singular. This is
not an error condition for this subroutine,
but it does indicate that CHISL or CHIDI 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,CMPLX,CONJG,REAL,SQRT
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