[ Arithmetic | Reference Manual | Alphabetic Index ]

# sqrt(+Number, -Result)

Evaluates the square root sqrt(Number) and unifies the resulting value with Result.

Number
  A number.
Result
  Output: float or breal.

## Description

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

        Result is sqrt(Number)

which should be preferred for portability.

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

### Modes and Determinism

- sqrt(+, -) is det

### Exceptions

(4) instantiation fault
  Number is not instantiated (non-coroutining mode only).
(24) number expected
  Number is not of a numeric type.
(20) arithmetic exception
  Illegal arithmetic operation: Number is negative.

## Examples

    Success:
        Result is sqrt(2.0).	% gives Result = 1.4142135623730951
        Result is sqrt(1.0).      	% gives Result = 1.0
        Result is sqrt(49).       	% gives Result = 7.0

    Error:
        Result is sqrt(-2).         % arithmetic exception

## See Also

is / 2