DPPFA(3F)							     DPPFA(3F)

NAME    [Toc]    [Back]

     DPPFA   - DPPFA factors a double precision	symmetric positive definite
     matrix stored in packed form.

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

SYNOPSYS    [Toc]    [Back]

      SUBROUTINE DPPFA(AP,N,INFO)

DESCRIPTION    [Toc]    [Back]

     On	Entry

     AP	DOUBLE PRECISION (N*(N+1)/2)
	the packed form	of a symmetric matrix  A .  The
	columns	of the upper triangle are stored sequentially
	in a one-dimensional array of length  N*(N+1)/2	.
	See comments below for details.

     N INTEGER
	the order of the matrix	 A .  On Return

     AP	an upper triangular matrix  R ,	stored in packed
	form, so that  A = TRANS(R)*R .

     INFO INTEGER
	= 0  for normal	return.
	= K  if	the leading minor of order  K  is not
	positive definite.  Packed Storage The following program segment will
     pack the upper triangle of	a symmetric matrix.
	K = 0
	DO 20 J	= 1, N
	DO 10 I	= 1, J
	K = K +	1
	AP(K) =	A(I,J)
	10    CONTINUE
	20 CONTINUE LINPACK.  This version dated 08/14/78 .  Cleve Moler,
     University	of New Mexico, Argonne National	Lab.  Subroutines and
     Functions BLAS DDOT Fortran DSQRT


									PPPPaaaaggggeeee 1111