SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
reserve MATRIX(*,*) as 5 by 7
The dimensionality of an array, then, is frozen either by explicit declaration in a define statement,
or when it is first referenced in an executable statement — which, of course, should be a reserve
statement. Although the dimensionality of an array may be apparent from the context, the explicit
declaration is recommended as an aid to program documentation. Once the array dimensionality
has been frozen, the array must be referenced consistently. Any inconsistent reference is detected
as an error during program compilation.
Subscript size expressions may be arithmetic expressions containing variables, including other subscripted
variables. If such expressions are real, they are rounded to integer before they are used
as array dimension specifiers. Thus, the statement:
reserve LIST(*) as N, TABLE (*,*) as N by 2*M
allocates space for the arrays LIST and TABLE where the space requirement is dependent on the values
of the variables N and M.
A subscript size expression should not evaluate to zero or a negative value. An attempt to reserve
space using a zero- or negative-valued size expression will cause a program to terminate with an
error message. If any subscript expression in a reserve statement evaluates to 1, there is only one
element allocated to that dimension of the array. The statement:
reserve X(*) as 1, Y(*,*) as 1 by 3
allocates space to an array X with one element, X(1), and a two-dimensional array Y with three elements,
Y(1,1), Y(1,2), and Y(1,3). For all practical purposes, these one- and two-dimensional
arrays are equivalent to the unsubscripted variable X and a one-dimensional array Y.
When two or more arrays are to be allocated with the same dimensions, they may be combined in
a list of array names. Thus, the following is acceptable:
reserve A (*,*), B(*,*), C(*,*) as 5 by 10
Any reserve statement can contain a sublist of this form among its list of arrays, as in:
reserve VECTOR(*) as 5,
A(*), B(*) and C(*) as 15,
LIST1(*) and LIST2(*) as N+M,
TABLE(*,*) as 3 by Y,
.
.
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