Double Exponential Moving Average over Welles Wilder Moving Average Formula

Algos, strategies, code
1

Can anyone help me with below formula as I am unable to find code for Double Exponential Moving Average.

Crossover of Double Exponential Moving Average of 50 Days over Welles Wilder Moving Average of 50 Days period.

Thanks in advance.

2

Double Exponential Moving Average is not defined in tradescript