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Function `std.math.exponential.logb`

Extracts the exponent of x as a signed integral value.


						
				real logb
				(
				

				  real x
				

				) pure nothrow @nogc @trusted;
				

				

				double logb
				(
				

				  double x
				

				) pure nothrow @nogc @trusted;
				

				

				float logb
				(
				

				  float x
				

				) pure nothrow @nogc @trusted;

If x is subnormal, it is treated as if it were normalized. For a positive, finite x:

1 <= x * FLT_RADIX^-logb(x) < FLT_RADIX

Special Values
x	logb(x)	divide by 0?
±∞	+∞	no
±0.0	-∞	yes

Example

writeln(logb(1.0)); // 0
writeln(logb(100.0)); // 6

writeln(logb(0.0)); // -real.infinity
writeln(logb(real.infinity)); // real.infinity
writeln(logb(-real.infinity)); // real.infinity

Authors

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

License

Boost License 1.0.