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NAG[f07mwc] NAG[nag_zhetri] - Inverse of complex Hermitian indefinite matrix, matrix already factorized by f07mrc (nag_zhetrf)
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Calling Sequence
f07mwc(uplo, a, ipiv, 'n'=n, 'fail'=fail)
nag_zhetri(. . .)
Parameters
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uplo - String;
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On entry: indicates how has been factorized.
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Constraint: "Nag_Upper" or "Nag_Lower". .
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a - Matrix(1..dim1, 1..dim2, datatype=complex[8], order=order);
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Note: this array may be supplied in Fortran_order or C_order , as specified by order. All array parameters must use a consistent order.
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If , the upper triangle of is stored in the upper triangular part of the array.
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If , the lower triangle of is stored in the lower triangular part of the array.
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ipiv - Vector(1..dim, datatype=integer[kernelopts('wordsize')/8]);
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Note: the dimension, dim, of the array ipiv must be at least .
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On entry: details of the interchanges and the block structure of , as returned by f07mrc (nag_zhetrf).
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'n'=n - integer; (optional)
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Default value: the dimension of the array a.
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On entry: , the order of the matrix .
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Constraint: . .
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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_zhetri (f07mwc) computes the inverse of a complex Hermitian indefinite matrix , where has been factorized by f07mrc (nag_zhetrf).
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Error Indicators and Warnings
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"NE_ALLOC_FAIL"
Dynamic memory allocation failed.
"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"
The block diagonal matrix is exactly singular.
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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 f07mjc (nag_dsytri).
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Examples
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>
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uplo := "Nag_Lower":
n := 4:
a := Matrix([[-4.981630459440283 +0*I , 0 +0*I , 0 +0*I , 0 +0*I ], [0.210214907090655 +0.1106935130516159*I , -7.724450141995383 +0*I , 0 +0*I , 0 +0*I ], [0.3100287981271241 -0.04333020743962702*I , -0.1518120207240102 -0.3742958425613706*I , -1.36 +0*I , 0 +0*I ], [0.5637050486508776 -0.2850349501519716*I , 0.339658279960361 -0.03031451811355639*I , 3.91 -1.5*I , -1.84 +0*I ]], datatype=complex[8], order='C_order'):
ipiv := Vector([1, 2, -1, -1], datatype=integer[kernelopts('wordsize')/8]):
NAG:-f07mwc(uplo, a, ipiv, 'n' = n):
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