SSIFA - SSIFA factors a real symmetric matrix by elimination with
To solve A*X = B , follow SSIFA by SSISL. To compute INVERSE(A)*C ,
follow SSIFA by SSISL. To compute DETERMINANT(A) , follow SSIFA by
SSIDI. To compute INERTIA(A) , follow SSIFA by SSIDI. To compute
INVERSE(A) , follow SSIFA by SSIDI.
the symmetric matrix to be factored.
Only the diagonal and upper triangle are used.
the leading dimension of the array A .
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.
an integer vector of pivot indices.
= 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 SSISL or SSIDI 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 SAXPY,SSWAP,ISAMAX Fortran ABS,AMAX1,SQRT
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