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NAG[f07gwc] NAG[nag_zpptri] - Inverse of complex Hermitian positive-definite matrix, matrix already factorized by f07grc (nag_zpptrf), packed storage
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Calling Sequence
f07gwc(uplo, n, ap, 'fail'=fail)
nag_zpptri(. . .)
Parameters
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uplo - String;
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Constraint: "Nag_Upper" or "Nag_Lower". .
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n - integer;
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On entry: , the order of the matrix .
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Constraint: . .
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ap - Vector(1..dim, datatype=complex[8]);
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Note: the dimension, dim, of the array ap must be at least .
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'fail'=fail - table; (optional)
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The NAG error argument, see the documentation for NagError.
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Description
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Purpose
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nag_zpptri (f07gwc) computes the inverse of a complex Hermitian positive-definite matrix , where has been factorized by f07grc (nag_zpptrf), using packed storage.
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Error Indicators and Warnings
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"NE_BAD_PARAM"
On entry, argument had an illegal value.
"NE_INT"
On entry, . Constraint: .
"NE_INTERNAL_ERROR"
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please consult NAG for assistance.
"NE_SINGULAR"
Element of the diagonal of the Cholesky factor is zero. The Cholesky factor is singular, and the inverse of cannot be computed.
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Further Comments
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The total number of real floating-point operations is approximately .
The real analogue of this function is f07gjc (nag_dpptri).
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Examples
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>
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uplo := "Nag_Lower":
n := 4:
ap := Vector([1.797220075561143 +0*I, 0.8401864749527325 +1.068316577423342*I, 1.316353439509685 +0*I, 1.057188279741849 -0.467388502622712*I, -0.4701749470106329 +0.3130658155999466*I, 1.560392977137124 +0*I, 0.233694251311356 -1.391037210186643*I, 0.08335250923944192 +0.03676071443037458*I, 0.9359617337923402 +0.9899692192815736*I, 0.6603332973655891 +0*I], datatype=complex[8], order='C_order'):
NAG:-f07gwc(uplo, n, ap):
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