Defined in header
float logbf( float arg );
double logb( double arg );
long double logbl( long double arg );
Extracts the value of the exponent from the floating-point argument
arg, and returns it as a floating-point value. Formally, the result is the integral part of log
r|arg| as a signed floating-point value, for non-zero arg, where
r is FLT_RADIX. If
arg is subnormal, it is treated as though it was normalized.
|arg||-||floating point value|
 Return value
The floating-point exponent.
Domain or range error may occur if
arg is zero.
The value of the exponent returned by logb is always 1 less than the exponent retuned by frexp because of the different normalization requirements: for the exponent
e returned by logb, |arg*r-e
| is between 1 and
r (typically between 1 and 2), but for the exponent
e returned by frexp, |arg*2-e
| is between 0.5 and 1.
|This section is incomplete|
Reason: no example
 See also
| decomposes a number into significand and a power of 2 |
| extracts exponent of the number |
| multiplies a number by FLT_RADIX raised to a power |