DSIFA man page on IRIX

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DSIFA(3F)							     DSIFA(3F)

NAME
     DSIFA   - DSIFA factors a double precision symmetric matrix by
     elimination with symmetric pivoting.

     To solve  A*X = B , follow DSIFA by DSISL.	 To compute  INVERSE(A)*C ,
     follow DSIFA by DSISL.  To compute	 DETERMINANT(A) , follow DSIFA by
     DSIDI.  To compute	 INERTIA(A) , follow DSIFA by DSIDI.  To compute
     INVERSE(A) , follow DSIFA by DSIDI.

SYNOPSYS
      SUBROUTINE DSIFA(A,LDA,N,KPVT,INFO)

DESCRIPTION
     On Entry

     A DOUBLE PRECISION(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.

     KPVT 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 DSISL or DSIDI 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 DAXPY,DSWAP,IDAMAX Fortran DABS,DMAX1,DSQRT

									Page 1

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