Atari 400

DIM (DI.)
8
ARRAYS AND
MATRICES
An array is a one-dimensional list of numb ers assigned to subscripted va riables ;
e.g., A(O), A(1), A(2). Subscripts range from 0 to the dimensioned value. Figure
8-1 illustrates a 7-element arra y.
A(O)
A(1)
A(2)
A(3)
A(4)
A(S)
A(6)
Figure 8-1. Example of an Array
A matrix, in this context, is a two-dimensional table co ntaining rows and col-
umns. Rows run horizontally and columns run v erticall y. Matrix elements are
stored by BASIC in row -m a jor order. This means that a ll the e lem ents of the
first row are stored first, followed by all the elements of the second row, etc .
Figure 8-2 illustrates a 7 x 4 matrix.
Columns
M(O,O) M(0,1) M(0,2)
M(0,3)
M(1,0)
M(1 ,1)
M(1,2)
M(1,3)
M(2,
0) M(2,1)
M(2,2)
M(2,3)
M(3,
0) M(3,1)
M(3,2)
M(3,3)
M(4,0) M(4,1) M(4,2) M(4,3)
M(5,
0) M(5,1) M(5,2) M(5,3)
M(6,0) M(6,1) M(6,2)
M(6,3)
Figure 8-2. Example of a Matrix
This section describes the two commands associated with arrays, matrices, and
strings, a nd how to load both arrays and matrices. The com~a nds in this se c-
tion are:
DIM
CLR
Format:
D M { svar(aexp) }
1
mvar(aexp[ ,aexp])
IJ{ ,svar(aexp) }tl
~ ,mvar(aexp[ ,aexp ... ] U
Examples: DIM A(100)
DIM M(6,3)
DIM B$(20)
used w ith STRINGS
An a ,v s and Matr·ices 41