How to use the natural number?

I have an equation that is

e^(x-y) and i have no idea how to implement the natural number into the arduino.

https://www.arduino.cc/en/Math/H

double exp (double __x) // function returns the exponential value of x.

Hi,

float e=2.71828;

Should do the trick.
Tom.. :slight_smile:

In C/C++ use the pow(x,y) function to calculate xy and exp(y) to calculate ey.