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NAG[f07adc] NAG[nag_dgetrf] - factorization of real by matrix
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Calling Sequence
f07adc(a, ipiv, 'm'=m, 'n'=n, 'fail'=fail)
nag_dgetrf(. . .)
Parameters
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a - Matrix(1..dim1, 1..dim2, datatype=float[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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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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'm'=m - integer; (optional)
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Default value: the first dimension of the array a.
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On entry: , the number of rows of the matrix .
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Constraint: . .
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'n'=n - integer; (optional)
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Default value: the second dimension of the array a.
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On entry: , the number of columns 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_dgetrf (f07adc) computes the factorization of a real by matrix.
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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: .
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"
is exactly zero. The factorization has been completed but the factor is exactly singular, and division by zero will occur if it is subsequently used to solve a system of linear equations or to invert .
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Examples
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>
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m := 4:
n := 4:
a := Matrix([[1.8, 2.88, 2.05, -0.89], [5.25, -2.95, -0.95, -3.8], [1.58, -2.69, -2.9, -1.04], [-1.11, -0.66, -0.59, 0.8]], datatype=float[8]):
ipiv := Vector(4, datatype=integer[kernelopts('wordsize')/8]):
NAG:-f07adc(a, ipiv, 'm' = m, 'n' = n):
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