z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

c
v A function is a sequence of instructions that calculates a single value. A list of
zero or more values enclosed in parentheses always follow a function name, as
in my_func(3.14159). See Functions.
v An array is a list of values. Values in the list are called elements of the array.
These elements are numbered, beginning at zero. We call such a number a
subscript, or index, of the array. Subscripts always appear in square brackets
after the array. For example, a[0] refers to element zero in the array a. The first
element of the array always has the subscript 0. If a subscript value is a
floating-point number, the fractional part is discarded to make the subscript into
an integer. For example, the following expressions all refer to the same element:
a[3] a[3.2] a[3.999]
The maximum number of elements in a bc array is in the range from 0 to
{BC_DIM_MAX}−1 inclusive. Unlike with many languages, you don’t need to
declare the size of an array. Elements are created dynamically as required, with
an initial value of zero.
Since parentheses always follow function names and square brackets always follow
array names, bc can distinguish between all three types of names—variable names,
function names, and array names. Therefore, you can have variables, functions,
and arrays with the same name. For example, foo may be a variable whereas foo()
is a function and foo[ ] is an array.
Built-in Variables
bc has a number of built-in variables that are used to control various aspects of the
interpreter. These are described in the following topics.
Scale
The scale value is the number of digits to be retained after the decimal point in
arithmetic operations. For example, if the scale is 3, each calculation retains at least
three digits after the decimal point. This means that:
5 / 3
has the value:
1.666
If –l is specified, the scale is set to 20; otherwise, the default scale is zero.
The variable scale holds the current scale value. To change scales, assign a new
value to scale, as in:
scale = 5
Since scale is just a regular bc variable, it can be used in the full range of bc
expressions.
The number of decimal places in the result of a calculation is affected not only by
the scale, but also by the number of decimal places in the operands of the
calculation. discusses this. Arithmetic Operations discusses this.
There is also a function scale, which can determine the scale of any expression.
For example, scale(1.1234) returns the result 4, which is the scale of the number
1.1234. The result of the scale function is always an integer (that is, it has the
scale of 0).
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