csifa.f
SUBROUTINE CSIFA (A, LDA, N, KPVT, INFO)
C***BEGIN PROLOGUE CSIFA
C***PURPOSE Factor a complex symmetric matrix by elimination with
C symmetric pivoting.
C***LIBRARY SLATEC (LINPACK)
C***CATEGORY D2C1
C***TYPE COMPLEX (SSIFA-S, DSIFA-D, CHIFA-C, CSIFA-C)
C***KEYWORDS LINEAR ALGEBRA, LINPACK, MATRIX FACTORIZATION, SYMMETRIC
C***AUTHOR Bunch, J., (UCSD)
C***DESCRIPTION
C
C CSIFA factors a complex symmetric matrix by elimination
C with symmetric pivoting.
C
C To solve A*X = B , follow CSIFA by CSISL.
C To compute INVERSE(A)*C , follow CSIFA by CSISL.
C To compute DETERMINANT(A) , follow CSIFA by CSIDI.
C To compute INVERSE(A) , follow CSIFA by CSIDI.
C
C On Entry
C
C A COMPLEX(LDA,N)
C the symmetric matrix to be factored.
C Only the diagonal and upper triangle are used.
C
C LDA INTEGER
C the leading dimension of the array A .
C
C N INTEGER
C the order of the matrix A .
C
C On Return
C
C A a block diagonal matrix and the multipliers which
C were used to obtain it.
C The factorization can be written A = U*D*TRANS(U)
C where U is a product of permutation and unit
C upper triangular matrices , TRANS(U) is the
C transpose of U , and D is block diagonal
C with 1 by 1 and 2 by 2 blocks.
C
C KVPT INTEGER(N)
C an integer vector of pivot indices.
C
C INFO INTEGER
C = 0 normal value.
C = K if the K-th pivot block is singular. This is
C not an error condition for this subroutine,
C but it does indicate that CSISL or CSIDI may
C divide by zero if called.
C
C***REFERENCES J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W.
C Stewart, LINPACK Users' Guide, SIAM, 1979.
C***ROUTINES CALLED CAXPY, CSWAP, ICAMAX
C***REVISION HISTORY (YYMMDD)
C 780814 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 891107 Corrected category and modified routine equivalence
C list. (WRB)
C 891107 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900326 Removed duplicate information from DESCRIPTION section.
C (WRB)
C 920501 Reformatted the REFERENCES section. (WRB)
C***END PROLOGUE CSIFA