Generating Arrays - IBM 5100 Apl Reference Manual

(
('
c
One of the simplest kinds of arrays, the vector, has only one dimension; it can be
thought of as a collection of elements arranged along a horizontal line. The num-
bers that indicate the positions of elements in an array are called indices. An element
can be selected from a vector by a single index, since a vector has only one dimen-
sion. The following example shows assigning a numeric and a character vector to two
variable names, Nand C; the names are then entered to display the values they re-
present:
N~5 6.2 -3 888 95.12
N
~;
6.2 -::5 aB8
(y~;.
:1.2
C~"
· ABCDEFG'
c
ABCDEFG
Generating Arrays
The most common way to generate an array is to specify the following: the shape
the array is to have-that is, the length of each coordinate; the values of the ele-
ments of the new array. The APL function that forms an array is the reshape
function. The symbol for the reshape function is p. The format of the function
used to generate a n array is
X p Y,
where
X
is the shape of the array and
Y
represents
the values for the elements of the array. For the left argument (X), you enter a
number for each coordinate to be generated; this number indicates the length of
the coordinate. Each number in the left argument must be separated by at least one
blank. The values of the elements of the new array are whatever you enter as the
right argument (Y). The instruction 7
p
A means that the array to be generated has
'one dimension (is a vector) seven elements in length, and that seven values are to
be supplied from whatever values are found stored under the name A. It does not
matter how many elements A has, as long as it has at least one element. If A has
fewer than seven elements, its elements are repeated as often as needed to provide
seven entries in the new vector. If A has more than seven elements, the first seven
are used. The following examples show generation of some vectors:
7(.>:1. 2 ]
:1.2:.3123:1.
2p12~5
123 :1.23
5(.)1 .
~5
1.3 1.3 1.3 1.3 1.3
An array with two coordinates (rows and columns) is called a matrix.
Columns
Rows
33