Fibonacci numbers in REXX

Example for versions REXX

This example uses iterative definition of Fibonacci numbers.

In REXX, an uninitialized variable has its name in uppercase as its value; e.g. numbers = ‘NUMBERS’

Line 4: Arrays are called “stem variables”. The root of a stem ends with a period. Elements of a stem are named by adding a value to the stem; e.g. fib.1, fib.first, etc. Additional dimensions may be used by adding another period and value; e.g., fib.1.3; To initialize all possible stem instances, assign a value to the stem name; e.g., fib. = 0 or fib. = ” 

 1  #!/usr/bin/rexx
 2  /* Calculate Fibonacci using an associative array */
 3
 4    fib.  = ''
 5    fib.1 = 1
 6    fib.2 = 1
 7    numbers = ''
 8
 9    do f = 3 to 16
10      e = f - 1; d = f - 2
11      fib.f = fib.e + fib.d
12    end
13
14    do n = 1 to 16
15      numbers = numbers fib.n','
16      fib.f = fib.e + fib.d
17    end
18
19    say numbers"..."
20  exit