logb

fnreal logb(real x) @trusted pure nothrow @nogc

Extracts the exponent of x as a signed integral value.

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

x logb(x) divide by 0?
±∞ +∞ no
±0.0 -∞ yes
fndouble logb(double x) @trusted pure nothrow @nogc

ditto

fnfloat logb(float x) @trusted pure nothrow @nogc

ditto