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1.2 DS ATRI

1.2.1 Contents

This DS stores the coefficients of the upper- (or lower-) triangular part of a full symmetric matrix.

DS ATRI consists of five arrays of predefined order.

Array ATR0:

General information.

This integer array contains 32 variables, consisting of a general description of the job (title, date, name), of DS ATRI (type, level, ...), and indicates the presence or absence of array ATR1.

1:20 TITRE

job title in 20 words of 4 characters,

21:22 DATE

the creation date in 2 words of 4 characters,

23:28 NOMCRE

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

29 'ATRI'

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 ATR1).

Array ATR1:

description of any supplementary arrays.

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

Array ATR2:

General matrix description.

This integer array contains 11 values.

1 NTYP

the matrix coefficients type,

2 NIND

the number of indices (here 1),

3 M1

the maximum value of this index,

4 NCODSA

the type of matrix storage,
1: symmetric matrix, only the lower-triangular part is stored, line per line,

5 NBLOC

the number of pages of the matrix,

6 NCOL

the maximum number of columns of a matrix page,

7 NBMAT

the number of matrices,

8 NCODST

the storage mode (here 1, i.e., by degrees of freedom),

9 ND

the number of degrees of freedom per node if it is constant, or 0,

10 NOE

the number of nodes,

11 NTDL

the matrix order,

Array ATR3:

Pointer to the last column of each page.

This integer array contains:

• ATR3(1) = 0,
• ATR3(i+1) = the number of the last column of page i of the matrix,

Array ATR4:

The matrix coefficients.

This array of type NTYP contains the a priori non-zero matrix coefficients:

• ATR4(k) = value of the k-th matrix coefficient.

1.2.2 Corresponding tools

Reading and writing a DS ATRI

A DS residing in M.M. is written in M.S. on a sequential access file.

This is a category 2 DS, where only the first 4 arrays and any associated arrays (described in array ATR1) are read (module SDLECT) or written (module SDECRI):

• when reading, array ATR4 is only addressed and the read is performed by the program via a READ command:

  READ(NFATRI) LE,(M(IAATR4-1+I),I=1,LE)

• when writing, array ATR4 is transferred via a WRITE command.

Printing a DS ATRI

The contents (total or partial) of a DS ATRI can be printed using module
[4] IMATRI. Preprocessor IMAGXX is used when a conversationnel (or interactive) call of IMATRI is desired.

Creation and manipulation modules for a DS ATRI

DS ATRI is created from a DS TAE, by assembling the element arrays, for example via module ASSATR.

Module CLATRI takes the prescribed boundary conditions into account, whereas module FACTOR factorises a ATRI type matrix.