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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

### 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