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

Evaluates the difference Number1 - Number2 and unifies the resulting value with Result.

Number1
  A number.
Number2
  A number.
Result
  Output: a number.

## Description

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

        Result is Number1 - Number2

which should be preferred for portability.

The result is of type breal if any of the arguments is a breal, else float if any of the arguments is a float, else rational if any of the arguments is a rational. Only when both arguments are integers is the result an integer.

In coroutining mode, if Number1 or Number2 are uninstantiated, the call to -/3 is delayed until these variables are instantiated.

### Modes and Determinism

- -(+, +, -) is det

### Exceptions

(4) instantiation fault
  Number1 or Number2 is not instantiated (non-coroutining mode only).
(24) number expected
  Number1 or Number2 is not of a numeric type.

## Examples

        Result is 5 - 2.            % gives Result = 3
        Result is 5 - -2.0.         % gives Result = 7.0

## See Also

is / 2