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Function `std.math.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
NAN	FP_ILOGBNAN	no

Example

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

Authors

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

License

Boost License 1.0.