DPOFA(3F)							     DPOFA(3F)

NAME    [Toc]    [Back]

     DPOFA   - DPOFA factors a double precision	symmetric positive definite
     matrix.

     DPOFA is usually called by	DPOCO, but it can be called directly with a
     saving in time if	RCOND  is not needed.  (time for DPOCO)	= (1 +
     18/N)*(time for DPOFA) .

SYNOPSYS    [Toc]    [Back]

      SUBROUTINE DPOFA(A,LDA,N,INFO)

DESCRIPTION    [Toc]    [Back]

     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 an upper	triangular matrix  R  so that  A = TRANS(R)*R
	where  TRANS(R)	 is the	transpose.
	The strict lower triangle is unaltered.
	If  INFO .NE. 0	, the factorization is not complete.

     INFO INTEGER
	= 0  for normal	return.
	= K  signals an	error condition.  The leading minor
	of order  K  is	not positive definite.	LINPACK.  This version dated
     08/14/78 .	 Cleve Moler, University of New	Mexico,	Argonne	National Lab.
     Subroutines and Functions BLAS DDOT Fortran DSQRT


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