[ Arithmetic | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]
# round(+Number, -Result)

Rounds Number to the nearest integral value of the same type
*Number*
- A number.
*Result*
- A variable or number.

## Description

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

which should be preferred for portability.
This operation works on all numeric types. The result value is the
integral value that is closest to Number (rounding to nearest). If
Number is exactly in the middle between two integers, the result
is the even one.

The result type is the same as the argument type. To convert the
type to integer, use integer/2.

In coroutining mode, if Number is uninstantiated, the call to round/2
is delayed until this variable is instantiated.

### Modes and Determinism

### Exceptions

*(4) instantiation fault *
- Number is not instantiated (non-coroutining mode only).
*(5) type error *
- Number and Result are numbers of different type.
*(24) number expected *
- Number is not of a numeric type.
*(24) number expected *
- Result is neither a number nor a variable.

## Examples

Success:
round(1.49, 1.0).
round(1.5, 2.0). (odd integer part)
round(2.5, 2.0).
round(2.51, 3.0). (even integer part)
round(3.5, 4.0).
round(-6.4, Result). (gives Result = -6.0)
round(3, 3).
Fail:
round(1, 0.0).
Error:
round(A, 6.0). (Error 4).
round(0.5, 0). (Error 5).
round(4 + 2.3, 6.0). (Error 24).
round(1, r). (Error 24).

## See Also

is / 2, floor / 2, ceiling / 2, truncate / 2, integer / 2