IBM 5100 Apl Reference Manual

36
The following table shows what the shapes and ranks are for the various types of
arrays:
Data
Type
Scalar
Vector
Matrix
N-rank
arrays
Empty Arrays
Shape pX
Rank p pX
No dimension (indicated by an empty vector). ·0
Number of elements.
Number of rows and the number of columns. 2
Each
number is the length of a coordinate. N
Although most arrays have one or more elements, arrays with no elements also
exist.
An array with no elements is called an empty array. Empty arrays are useful
when creating lists (see Catenation in this chapter) or when branching in a user-
defined function (see Chapter 6).
Following are
some ways to generate empty arrays:
• Assign
10 to a variable name to generate an empty vector:
EVECTOR-E" \.0
[VECTOR
An empty array is indicated
------------- by a blank display.
r:iEVECTOR
0,
'-. ____________ The shape of the empty vector
is zero (zero elements).
• Use a zero length coordinate when generating a multidimensional array:
:3 0
This matrix has three rows
EMATRIX:l.~<3 O~) \ 0- and no (0) columns.
EMATJ~IX:1.
A blank output display
~)EMAT J~ I X 1.
• A function might generate an empty vector as its result; for example, finding the
shape of a scalar:
A
blank output display.

IBM 5100 Specifications

General

Release Year	1975
RAM	16 KB - 64 KB
Storage	204 KB tape drive
Display	5-inch CRT
Operating System	APL/BASIC
Processor	IBM PALM (1.9 MHz)