Calculates the value of natural logarithm base e raised to the power d and subtracts 1 from the result.
long double expm1l(long double d);
d Power value to which natural logarithm base e is to be raised
Normal: Value obtained by subtracting 1 from natural logarithm base e raised to the power d
Abnormal: Range error: Returns -HUGE_VAL, –HUGE_VALF, or –HUGE_VALL depending on the function.
expm1(d) provides more accurate calculation than exp(x) – 1 even when d is near to 0.