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

define sum_c(a[ ],b[ ],l) {
auto i
for (i=0; i < l; ++i) c[i] = a[i] + b[i]
}
refers to an external array named c, which is the element-by-element sum of two
other arrays. If c did not exist prior to calling sum_c, it is created dynamically. After
the program has called sum_c, statements in the program or in functions can refer
to array c.
Functions usually require a return statement. This has the form:
return (expression)
The argument expression is evaluated and used as the result of the function. The
expression must have a single numeric value; it cannot be an array.
A return statement ends a function, even if there are more statements left in the
function. For example:
define abs(i) {
if (i < 0) return (-i)
return (i)
}
is a function that returns the absolute value of its argument. If i is less than zero,
the function takes the first return; otherwise, it takes the second.
A function can also end by running the last statement in the function. If so, the
result of the function is zero. The function sum_c is an example of a function that
does not have a return statement. The function does not need a return statement,
because its work is to calculate the external array c, not to calculate a single value.
Finally, if you want to return from a function, but not return a value you can use
return() or simply return. If there are no parameters to the return statement, a
default value of zero is returned.
Built-in Functions
bc has a number of built-in functions that perform various operations. These
functions are similar to user-defined functions. You do not have to define them
yourself, however; they are already set up for you. These functions are:
length(expression)
Calculates the total number of decimal digits in expression. This includes
digits both before and after the decimal point. The result of length() is an
integer. For example, length(123.456) returns 6.
scale(expression)
Returns the scale of expression. For example, scale(123.456) returns 3.
The result of scale() is always an integer. Subtracting the scale of a
number from the length of a number lets you determine the number of digits
before the decimal point.
sqrt(expression)
Calculates the square root of the value of expression. The result is
truncated in the least significant decimal place (not rounded). The scale of
the result is the scale of expression, or the value of scale(), whichever is
larger.
You can use the following functions if –l is specified on the command line. If it is
not, the function names are not recognized. There are two names for each function:
bc
Chapter 2. Shell command descriptions 61