NAG FL Interface
f01vmf (ztfttp)

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FL Name Style:

FL Specification Language:

1 Purpose

f01vmf copies a complex triangular matrix, stored in a Rectangular Full Packed (RFP) format array, to a standard packed format array.

2 Specification

Fortran Interface
Subroutine f01vmf ( transr, uplo, n, ar, ap, info)
Integer, Intent (In) :: n
Integer, Intent (Out) :: info
Complex (Kind=nag_wp), Intent (In) :: ar(n*(n+1)/2)
Complex (Kind=nag_wp), Intent (Out) :: ap(n*(n+1)/2)
Character (1), Intent (In) :: transr, uplo
C Header Interface
#include <nag.h>
void  f01vmf_ (const char *transr, const char *uplo, const Integer *n, const Complex ar[], Complex ap[], Integer *info, const Charlen length_transr, const Charlen length_uplo)
The routine may be called by the names f01vmf, nagf_matop_ztfttp or its LAPACK name ztfttp.

3 Description

f01vmf packs a complex n×n triangular matrix A, stored in RFP format, to packed format. This routine is intended for possible use in conjunction with routines from Chapters F06, F07 and F16 where some routines that use triangular matrices store them in RFP format. The RFP storage format is described in Section 3.3.3 in the F07 Chapter Introduction and the packed storage format is described in Section 3.3.2 in the F07 Chapter Introduction.

4 References

Gustavson F G, Waśniewski J, Dongarra J J and Langou J (2010) Rectangular full packed format for Cholesky's algorithm: factorization, solution, and inversion ACM Trans. Math. Software 37, 2

5 Arguments

1: transr Character(1) Input
On entry: specifies whether the normal RFP representation of A or its conjugate transpose is stored.
The RFP representation of the matrix A is stored.
The conjugate transpose of the RFP representation of the matrix A is stored.
Constraint: transr='N' or 'C'.
2: uplo Character(1) Input
On entry: specifies whether A is upper or lower triangular.
A is upper triangular.
A is lower triangular.
Constraint: uplo='U' or 'L'.
3: n Integer Input
On entry: n, the order of the matrix A.
Constraint: n0.
4: ar(n×(n+1)/2) Complex (Kind=nag_wp) array Input
On entry: the upper or lower n×n triangular matrix A (as specified by uplo) in either normal or transposed RFP format (as specified by transr). The storage format is described in Section 3.3.3 in the F07 Chapter Introduction.
5: ap(n×(n+1)/2) Complex (Kind=nag_wp) array Output
On exit: the n×n triangular matrix A, packed by columns.
More precisely,
  • if uplo='U', the upper triangle of A is stored with element Aij in ap(i+j(j-1)/2) for ij;
  • if uplo='L', the lower triangle of A is stored with element Aij in ap(i+(2n-j)(j-1)/2) for ij.
6: info Integer Output
On exit: info=0 unless the routine detects an error (see Section 6).

6 Error Indicators and Warnings

If info=-i, argument i had an illegal value. An explanatory message is output, and execution of the program is terminated.
Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
f01vmf is not threaded in any implementation.

9 Further Comments


10 Example

This example reads in a triangular matrix in RFP format and copies it to packed format.

10.1 Program Text

Program Text (f01vmfe.f90)

10.2 Program Data

Program Data (f01vmfe.d)

10.3 Program Results

Program Results (f01vmfe.r)