source: azure_iot_hub/trunk/musl-1.1.18/src/math/logbf.c@ 388

#include <math.h>

float logbf(float x)
{
        if (!isfinite(x))
                return x * x;
        if (x == 0)
                return -1/(x*x);
        return ilogbf(x);
}