Example of a Function

Calculations represented by functions often require many instructions. For instance, the simple calculation for finding the highest number in a group of three numbers, might be written as follows:

Finding a Maximum Number

/***************************** REXX ********************************/
/* This exec receives three numbers from a user and analyzes which */
/* number is the greatest.                                         */
/*******************************************************************/

 PARSE ARG number1, number2, number3 .

 IF number1 > number2 THEN
    IF number1 > number3 THEN
       greatest = number1
    ELSE
       greatest = number3
 ELSE
    IF number2 > number3 THEN
       greatest = number2
    ELSE
       greatest = number3

 RETURN greatest

Rather than writing multiple instructions every time you want to find the maximum of a group of three numbers, you can use a built-in function that does the calculation for you and returns the maximum number. The function is called MAX and is used as follows:

MAX(number1,number2,number3,…)

To find the maximum of 45, -2, number, 199, and put the maximum into the symbol biggest, write the following instruction:

biggest = MAX(45,-2,number,199)