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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
A variable or 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

```Success:
-(5, 2, 3).            (gives Result = 3)
-(5, -2.0, Result).    (gives Result = 7.0)
Fail:
-(1, 2, 3).
-(1, 2, 3.0).
-(5, 2, r).
Error:
-(A, 2, 6).             (Error 4).
-(4 + 1, 2, 3).         (Error 24).

```