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Function std.math.exponential.ilogb

Extracts the exponent of x as a signed integral value.

int ilogb(T) (
  const T x
) pure nothrow @nogc @trusted
if (isFloatingPoint!T);

int ilogb(T) (
  const T x
) pure nothrow @nogc @safe
if (isIntegral!T && isUnsigned!T);

int ilogb(T) (
  const T x
) pure nothrow @nogc @safe
if (isIntegral!T && isSigned!T);

If x is not a special value, the result is the same as cast(int) logb(x).

Special Values
x ilogb(x) Range error?
0 FP_ILOGB0 yes
±∞ int.max no


writeln(ilogb(1)); // 0
writeln(ilogb(3)); // 1
writeln(ilogb(3.0)); // 1
writeln(ilogb(100_000_000)); // 26

writeln(ilogb(0)); // FP_ILOGB0
writeln(ilogb(0.0)); // FP_ILOGB0
writeln(ilogb(double.nan)); // FP_ILOGBNAN
writeln(ilogb(double.infinity)); // int.max


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


Boost License 1.0.