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# Function `std.math.exponential.frexp`

Separate floating point value into significand and exponent.

``` T frexp(T) (   const T value,   out int exp ) pure nothrow @nogc @trusted if (isFloatingPoint!T); ```

## Returns

Calculate and return x and exp such that value =x*2exp and .5 <= |x| < 1.0

x has same sign as value.

Special Values
value returns exp
±0.0 ±0.0 0
+∞ +∞ int.max
-∞ -∞ int.min
±NAN ±NAN int.min

## Example

``````import std.math.operations : isClose;

int exp;
real mantissa = frexp(123.456L, exp);

assert(isClose(mantissa * pow(2.0L, cast(real) exp), 123.456L));

assert(frexp(-real.nan, exp) && exp == int.min);
assert(frexp(real.nan, exp) && exp == int.min);
assert(frexp(-real.infinity, exp) == -real.infinity && exp == int.min);
assert(frexp(real.infinity, exp) == real.infinity && exp == int.max);
assert(frexp(-0.0, exp) == -0.0 && exp == 0);
assert(frexp(0.0, exp) == 0.0 && exp == 0);
``````

## Authors

Walter Bright, Don Clugston, Conversion of CEPHES math library to D by Iain Buclaw and David Nadlinger