DPODI(3F)DPODI(3F)NAMEDPODI - DPODI computes the determinant and inverse of a certain double
precision symmetric positive definite matrix (see below) using the
factors computed by DPOCO, DPOFA or DQRDC.
SYNOPSYS
SUBROUTINE DPODI(A,LDA,N,DET,JOB)
DESCRIPTION
On Entry
A DOUBLE PRECISION(LDA, N)
the output A from DPOCO or DPOFA
or the output X from DQRDC.
LDA INTEGER
the leading dimension of the array A .
N INTEGER
the order of the matrix A .
JOB INTEGER
= 11 both determinant and inverse.
= 01 inverse only.
= 10 determinant only. On Return
A If DPOCO or DPOFA was used to factor A , then
DPODI produces the upper half of INVERSE(A) .
If DQRDC was used to decompose X , then
DPODI produces the upper half of inverse(TRANS(X)*X)
where TRANS(X) is the transpose.
Elements of A below the diagonal are unchanged.
If the units digit of JOB is zero, A is unchanged.
DET DOUBLE PRECISION(2)
determinant of A or of TRANS(X)*X if requested.
Otherwise not referenced.
Determinant = DET(1) * 10.0**DET(2)
with 1.0 .LE. DET(1) .LT. 10.0
or DET(1) .EQ. 0.0 . Error Condition
A division by zero will occur if the input factor contains a zero on the
diagonal and the inverse is requested. It will not occur if the
subroutines are called correctly and if DPOCO or DPOFA has set INFO .EQ.
0 . LINPACK. This version dated 08/14/78 . Cleve Moler, University of
New Mexico, Argonne National Lab. Subroutines and Functions BLAS
DAXPY,DSCAL Fortran MOD
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