Problem with find the mean ATR SD

[purecnx]

double atrMean = CalculateATRMean(ATR_Period);

double CalculateATRMean(int period) {
double sum = 0;
for (int i = 1; i <= period; i++) {
sum += iATR(Symbol(), 0, period, i);
}
return sum / period;
}

double CalculateSD(double &values[], int size, double mean) {
double variance = 0.0;
for (int i = 0; i < size; i++) {
variance += MathPow(values[i] - mean, 2);
}
return MathSqrt(variance / size);
}

USE THIS CODE IN MQL

[link text](link url)https://fxdreema.com/shared/M40hxlHTb

How can i declareation Function in Global?

Compilation errors
'CalculateATRMean' - function not defined
'CalculateATRMean' - function declarations are allowed on global, namespace or class scope only
'CalculateSD' - function declarations are allowed on global, namespace or class scope only

[purecnx]

@fxDreema @l-andorrà

[sktsec]

In the source code, there is a dedicated session for custom function.