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- DDDDSSSSIIIIDDDDIIII((((3333FFFF)))) DDDDSSSSIIIIDDDDIIII((((3333FFFF))))
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- NNNNAAAAMMMMEEEE
- DSIDI - DSIDI computes the determinant, inertia and inverse of a double
- precision symmetric matrix using the factors from DSIFA.
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- SSSSYYYYNNNNOOOOPPPPSSSSYYYYSSSS
- SUBROUTINE DSIDI(A,LDA,N,KPVT,DET,INERT,WORK,JOB)
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- DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
- On Entry
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- AAAA DOUBLE PRECISION(LDA,N)
- the output from DSIFA.
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- LLLLDDDDAAAA INTEGER
- the leading dimension of the array A.
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- NNNN INTEGER
- the order of the matrix A.
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- KKKKPPPPVVVVTTTT INTEGER(N)
- the pivot vector from DSIFA.
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- WWWWOOOORRRRKKKK DOUBLE PRECISION(N)
- work vector. Contents destroyed.
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- JJJJOOOOBBBB INTEGER
- JOB has the decimal expansion ABC where
- if C .NE. 0, the inverse is computed,
- if B .NE. 0, the determinant is computed,
- if A .NE. 0, the inertia is computed.
- For example, JOB = 111 gives all three. On Return Variables not
- requested by JOB are not used.
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- AAAA contains the upper triangle of the inverse of
- the original matrix. The strict lower triangle
- is never referenced.
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- DDDDEEEETTTT DOUBLE PRECISION(2)
- determinant of original matrix.
- DETERMINANT = DET(1) * 10.0**DET(2)
- with 1.0 .LE. DABS(DET(1)) .LT. 10.0
- or DET(1) = 0.0.
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- IIIINNNNEEEERRRRTTTT INTEGER(3)
- the inertia of the original matrix.
- INERT(1) = number of positive eigenvalues.
- INERT(2) = number of negative eigenvalues.
- INERT(3) = number of zero eigenvalues. Error Condition
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- AAAA division by zero may occur if the inverse is requested and DSICO has
- set RCOND .EQ. 0.0 or DSIFA has set INFO .NE. 0 . LINPACK. This
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- PPPPaaaaggggeeee 1111
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- DDDDSSSSIIIIDDDDIIII((((3333FFFF)))) DDDDSSSSIIIIDDDDIIII((((3333FFFF))))
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- version dated 08/14/78 . James Bunch, Univ. Calif. San Diego, Argonne
- Nat. Lab Subroutines and Functions BLAS DAXPY,DCOPY,DDOT,DSWAP Fortran
- DABS,IABS,MOD
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- PPPPaaaaggggeeee 2222
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