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man pages->IRIX man pages -> complib/SPODI (3)
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### Contents

```
SPODI(3F)							     SPODI(3F)

```

### NAME[Toc][Back]

```     SPODI   - SPODI computes the determinant and inverse of a certain real
symmetric positive	definite matrix	(see below) using the factors computed
by	SPOCO, SPOFA or	SQRDC.

```

### SYNOPSYS[Toc][Back]

```      SUBROUTINE SPODI(A,LDA,N,DET,JOB)
```

### DESCRIPTION[Toc][Back]

```     On	Entry

A REAL(LDA, N)
the output  A  from SPOCO or SPOFA
or the output  X  from SQRDC.

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 SPOCO	or SPOFA was used to factor  A , then
SPODI produces the upper half of INVERSE(A) .
If SQRDC was used to decompose	X , then
SPODI 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 REAL(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 SPOCO or SPOFA 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
SAXPY,SSCAL Fortran MOD

PPPPaaaaggggeeee 1111```
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