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rem(+Number1, +Number2, -Result)

-Result is +Number1 rem +Number2

Evaluates the remainder Number1 rem Number2 and unifies the resulting value with Result.
Number1
Integer.
Number2
Integer.
Result
Output: integer.

Description

Evaluates the remainder Number1 rem Number2 and unifies the resulting value with Result.

The modulus operation computes the remainder corresponding to the truncating division //. The following relation always holds: 

    X =:= (X rem Y) + (X // Y) * Y.
The result Result is either zero, or has the same sign as Number1. The absolute value of Result does not depend on the signs of the arguments.

This predicate can be used as a function in arithmetic expressions. In coroutining mode, if Number1 or Number2 are uninstantiated, the call to rem/3 is delayed until these variables are instantiated.

See also the mod operation, whose result only differs when the arguments have opposite signs.

Modes and Determinism

Exceptions

(4) instantiation fault
Number1 or Number2 is not instantiated (non-coroutining mode only).
(5) type error
Number1 or Number2 is a number but not an integer.
(20) arithmetic exception
Illegal arithmetic operation: Number2 is zero
(24) number expected
Number1 or Number2 is not of a numeric type.

Examples

Success:
      X is  10 rem  3.		% gives X =  1
      X is -10 rem  3.		% gives X = -1
      X is  10 rem -3.		% gives X =  1
      X is -10 rem -3.		% gives X = -1

Error:
      rem(2, 0, Result).        % arithmetic exception

See Also

is / 2, // / 3, mod / 3