dppdi.f
SUBROUTINE DPPDI (AP, N, DET, JOB)
C***BEGIN PROLOGUE DPPDI
C***PURPOSE Compute the determinant and inverse of a real symmetric
C positive definite matrix using factors from DPPCO or DPPFA.
C***LIBRARY SLATEC (LINPACK)
C***CATEGORY D2B1B, D3B1B
C***TYPE DOUBLE PRECISION (SPPDI-S, DPPDI-D, CPPDI-C)
C***KEYWORDS DETERMINANT, INVERSE, LINEAR ALGEBRA, LINPACK, MATRIX,
C PACKED, POSITIVE DEFINITE
C***AUTHOR Moler, C. B., (U. of New Mexico)
C***DESCRIPTION
C
C DPPDI computes the determinant and inverse
C of a double precision symmetric positive definite matrix
C using the factors computed by DPPCO or DPPFA .
C
C On Entry
C
C AP DOUBLE PRECISION (N*(N+1)/2)
C the output from DPPCO or DPPFA.
C
C N INTEGER
C the order of the matrix A .
C
C JOB INTEGER
C = 11 both determinant and inverse.
C = 01 inverse only.
C = 10 determinant only.
C
C On Return
C
C AP the upper triangular half of the inverse .
C The strict lower triangle is unaltered.
C
C DET DOUBLE PRECISION(2)
C determinant of original matrix if requested.
C Otherwise not referenced.
C DETERMINANT = DET(1) * 10.0**DET(2)
C with 1.0 .LE. DET(1) .LT. 10.0
C or DET(1) .EQ. 0.0 .
C
C Error Condition
C
C A division by zero will occur if the input factor contains
C a zero on the diagonal and the inverse is requested.
C It will not occur if the subroutines are called correctly
C and if DPOCO or DPOFA has set INFO .EQ. 0 .
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 DAXPY, DSCAL
C***REVISION HISTORY (YYMMDD)
C 780814 DATE WRITTEN
C 890831 Modified array declarations. (WRB)
C 890831 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 DPPDI