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1.16 DS VVPR

1.16.1 Contents

This DS stores information corresponding to the eigenvalues and vectors of a system.

DS VVPR is composed of five arrays of predefined order.

Array VVP0:

General information.

This integer array contains 32 variables, consisting of a general description of the job (title, date, name), of DS VVPR (type, level, ...), and indicates the presence or absence of array VVP1.

1:20 TITRE

the job title in 20 words of 4 characters,

21:22 DATE

the data of creation in 2 words of 4 characters,

23:28 NOMCRE

the creator's name in 6 words of 4 characters,

29 'VVPR'

the DS type,

30 NIVEAU

the DS level,

31 ETAT

a reserved parameter,

32 NTACM

the number of supplementary arrays associated with the DS (they are described in array VVP1).

Array VVP1:

Description of any supplementary arrays.

This array is analogous to array B1 of DS B (see this DS).

Array VVP2:

General description.

This integer array contains 7 values.

1 NTYVA

the type of eigenvalues,

2 NVALPR

the number of eigenvalues,

3 NTYVE

the type of eigenvectors,

4 NCVEC

the number of eigenvector components,

5 NEBER

the existence (1) or not (0) of an error bound for the eigenvalues,

6 NGT

the number of couples in array VVP3, VVP4 on file,

7 NEXVEC

0 if there are no eigenvectors, 1 otherwise.

Array VVP3:

The eigenvalues.

This NTYVA type array contains:

• VVP3(i) eigenvalue i for i = 1, NVALPR, and
• if NEBER = 1, VVP3(NVALPR+i) the semi-interval of the error for i = 1, NVALPR.

Array VVP4:

The eigenvectors.

This NTYVE type array, which exists if NEXVEC equals 1, contains:

• VVP4(i,j) component i of vector j, for i = 1, NCVEPR and j = 1, NVALPR.

1.16.2 Corresponding tools

Reading and writing a DS VVPR

A DS residing in core is written partially (it is a category 2 DS); only its 3 generic arrays and any associated arrays described in array VVP1 are written to sequential file via module SDECRI.

Similarly, a DS residing on file is read and transferred partially (its 3 generic arrays and any associated arrays described in array VVP1) to main memory via module SDLECT; only arrays VVP3 and VVP4 are addressed:

• When reading, only arrays VVP3 and VVP4 are addressed and the read is performed by the program via a READ type command.
• When writing, its arrays are transferred via a WRITE type command.

Printing a DS VVPR

The contents (total or partial) of a DS VVPR can be printed by module IMVVPR. Preprocessor IMAGXX is used when a conversational call of IMVVPR is desired.

Creation and modification modules for a DS VVPR

DS VVPR is created using different modules corresponding to different methods (Lanczos, sub-space, etc.).