Numeric comparisons

The comparison operators are listed in Comparison. You can use any of these for comparing numeric strings. However, you should not use ==, \==, ¬==, >>, \>>, ¬>>, <<, \<<, and ¬<< for comparing numbers because leading and trailing blanks and leading zeros are significant with these operators.

A comparison of numeric values is effected by subtracting the two numbers (calculating the difference) and then comparing the result with 0. That is, the operation: 
A ? Z
where ? is any numeric comparison operator, is identical with: 
(A - Z) ? '0'

It is, therefore, the difference between two numbers, when subtracted under REXX subtraction rules, that determines their equality.

A quantity called fuzz affects the comparison of two numbers. This controls the amount by which two numbers may differ before being considered equal for the purpose of comparison. The FUZZ value is set by the instruction:
Read syntax diagramSkip visual syntax diagramNUMERIC FUZZexpression;

Here expression must result in a positive whole number or zero. The default is 0.

The effect of FUZZ is to temporarily reduce the value of DIGITS by the FUZZ value for each numeric comparison. That is, the numbers are subtracted under a precision of DIGITS minus FUZZ digits during the comparison. Clearly the FUZZ setting must be less than DIGITS.

Thus if DIGITS = 9 and FUZZ = 1, the comparison is carried out to 8 significant digits, just as though NUMERIC DIGITS 8 had been put in effect for the duration of the operation.

Example: 
Numeric digits 5
Numeric fuzz 0
say  4.9999 = 5     /* Displays "0"    */
say  4.9999 < 5     /* Displays "1"    */
Numeric fuzz 1
say  4.9999 = 5     /* Displays "1"    */
say  4.9999 < 5     /* Displays "0"    */