naginterfaces.library.matop.dtpttr

naginterfaces.library.matop.dtpttr(uplo, n, ap)

dtpttr unpacks a real triangular matrix, stored in a standard packed format array, to a full format array.

For full information please refer to the NAG Library document for f01vc

https://support.nag.com/numeric/nl/nagdoc_30.2/flhtml/f01/f01vcf.html

Parameters

uplostr, length 1

Specifies whether $A$ is upper or lower triangular.

$uplo=\text{'U'}$

$A$ is upper triangular.

$uplo=\text{'L'}$

$A$ is lower triangular.

nint

$n$, the order of the matrix $A$.

apfloat, array-like, shape $(n\times (n+1)/2)$

The $n\times n$ triangular matrix $A$, packed by columns.

Returns

afloat, ndarray, shape $(n,n)$

The triangular matrix $A$.

Raises

NagValueError

(errno $-1$)

On entry, error in parameter $uplo$.

Constraint: $uplo=\text{'U'}$ or $\text{'L'}$.

(errno $-2$)

On entry, error in parameter $n$.

Constraint: $n\ge 0$.

Notes

dtpttr unpacks a real $n\times n$ triangular matrix $A$, stored in an array of length $n(n+1)/2$, to conventional storage in a full format array. This function is intended for possible use in conjunction with functions from submodule blas, submodule blast, submodule lapacklin and submodule lapackeig where some functions use triangular matrices stored in the packed form. Packed storage format is described in the F07 Introduction.