Numerical calculation of Darcy-Weisbach friction factor

The darcy-weisbach friction factor is calculated using the Colebrook-White equation via the secant method.

This function takes in a given reynolds number, relative roughness, and residual value. Utilizing these three values the function iterates though the colebrook-white equation to calculate the darcy-weisbach friction factor utilizing the secant method. Since the secant method is utilized, the function breaks down a extremely high reynolds numbers. This can be resolved by adjusting the values of the first two iterations of the friction factor calculation to a value closer to the actual value.