//+------------------------------------------------------------------+
//|                                                          Std.mq5 |
//|                                  Copyright 2026, Niquel Mendoza. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2026, Niquel Mendoza."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property strict

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
bool StandartVec(const vector& in, vector& out)
 {
  double std = in.Std();
  if(std < DBL_EPSILON)
    return false;
  std = 1.0 / std;

//---
  const double mean = in.Mean();
  out = (in - mean) * std;
  return true;
 }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
bool OnePassWelford(const vector& X, vector& out)
 {
//---
  const ulong fs = X.Size();
  double mean_val = 0.0;
  double m2 = 0.0;
  for(ulong i = 0; i < fs; i++)
   {
    const double v = X[i];
    out[i] = v;

    //---
    const double del = v - mean_val;
    mean_val += del / (i + 1);

    //---
    const double del2 = v - mean_val;

    //---
    m2 += del * del2;
   }

//--- calc std
  double std = m2 / fs; // var

//--- check std
  std = MathSqrt(std);
  if(std < DBL_EPSILON)
    return false;

//--- inv
  std = 1.0 / std; // inversa

//--- final
  out -= mean_val;
  out *= std;
  return true;
 }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
bool TwoPassStd(const vector &X, vector &out)
 {
  const ulong n = X.Size();
  if(n == 0)
    return false;

//---
  const double s_inv = 1.0 / double(n);

//---
  double mean_val = 0.0;
  for(ulong i = 0; i < n; i++)
    mean_val += X[i];
  mean_val *= s_inv;

//---
  double sumSq = 0.0;
  out.Resize(n);
  for(ulong i = 0; i < n; i++)
   {
    const double d = X[i] - mean_val;
    out[i] = d;
    sumSq += d * d;
   }
  const double var = sumSq * s_inv;

//---
  double std = MathSqrt(var);
  if(std < DBL_EPSILON)
    return false;
  std = 1.0 / std;

//--- final: centrado + escalado, vectorizado
  out *= std;
  return true;
 }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
vector Ran()
 {
  vector v(1000);
  for(int i = 0; i < 1000; i++)
   {
    v[i] = (double)MathRand();
   }
  return v;
 }

//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
 {
//---
  MathSrand(10);
  double vs = 0.0;

  ulong a = GetMicrosecondCount();
  for(int i = 1; i < 100000; i++)
   {
    vector v = Ran();
    StandartVec(v, v);
    vs += v[0];
   }
  ulong b = GetMicrosecondCount();

  Print("native: ", (b - a), " vs : ", vs);

  vs = 0.0;
  MathSrand(10);

  a = GetMicrosecondCount();
  for(int i = 1; i < 100000; i++)
   {
    vector v = Ran();
    OnePassWelford(v, v);
    vs += v[0];
   }
  b = GetMicrosecondCount();

  Print("1p: ", (b - a), " vs : ", vs);

  vs = 0.0;
  MathSrand(10);

  a = GetMicrosecondCount();
  for(int i = 1; i < 100000; i++)
   {
    vector v = Ran();
    TwoPassStd(v, v);
    vs += v[0];
   }
  b = GetMicrosecondCount();

  Print("2p: ", (b - a), " vs : ", vs);

 }
//+------------------------------------------------------------------+