CPPFA(3)

SYNOPSIS
SUBROUTINE CPPFA (AP, N, INFO)

NAME
cppfa - Factor a complex Hermitian positive definite matrix stored in packed form.

LIBRARY
SLATEC (LINPACK)

CATEGORY
D2D1B

TYPE
COMPLEX (SPPFA-S, DPPFA-D, CPPFA-C)

KEYWORDS
LINEAR ALGEBRA, LINPACK, MATRIX FACTORIZATION, PACKED, POSITIVE DEFINITE

AUTHOR
Moler, C. B., (U. of New Mexico)

DESCRIPTION
CPPFA factors a complex Hermitian positive definite matrix stored in packed form. CPPFA is usually called by CPPCO, but it can be called directly with a saving in time if RCOND is not needed. (Time for CPPCO) = (1 + 18/N)*(Time for CPPFA) . On Entry AP COMPLEX (N*(N+1)/2) the packed form of a Hermitian 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 = CTRANS(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 Hermitian 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

REFERENCES
J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W. Stewart, LINPACK Users' Guide, SIAM, 1979.

ROUTINES CALLED
CDOTC

REVISION HISTORY (YYMMDD)
780814 DATE WRITTEN
890831 Modified array declarations. (WRB)
890831 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)
900326 Removed duplicate information from DESCRIPTION section. (WRB)
920501 Reformatted the REFERENCES section. (WRB)