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# rem(+Number1, +Number2, -Result)

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

## Description

This predicate is used by the ECLiPSe compiler to expand evaluable
arithmetic expressions. So the call to rem(Number1, Number2, Result) is
equivalent to
Result is Number1 rem Number2

which should be preferred for portability.
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.
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