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Function `std.math.logb`

Extracts the exponent of x as a signed integral value.


						
				real logb
				(
				

				  real x
				

				) 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

assert(logb(1.0).feqrel(0.0) > 16);
assert(logb(100.0).feqrel(6.0) > 16);

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.