Question on trading system filters

Hello

Sorry for being rather a "nube" to all this, but I have been reading lots
on the forums before joining up. I was reading some very interesting
posts about NonLagMA filters. Two questions for some kind hearted
colleague who will forgive nubey questions:

(1) What is an "EA" that folk always talk about wanting to build?

(2) What is a "pctfilter" included in the NonLagMA trading indicator?

Many thanks!!

Hi.

I suspect you've figured these out by now, but I'll share some things I found just in case.

I believe "EA" is Expert Advisor -- basically, an automated trading system.

Your second question is a bit tougher. I found some code that looks like C or C++. I haven't read any C code in 20 years so this is tough to figure out. This code is for Metatrader 4. You can find the references to pctFilter in the code -- which I'll paste below. It would be great to see this in Matlab. It would be clear for me at that point. Anyway, hope this is helpful.

Enjoy,
Ngawang

#property indicator_chart_window
#property indicator_buffers 3
#property indicator_color1 Orange
#property indicator_width1 2
#property indicator_color2 SkyBlue
#property indicator_width2 2
#property indicator_color3 Tomato
#property indicator_width3 2

//---- input parameters
extern int Price = 0; //Apply to Price(0-Close;1-Open;2-High;3-Low;4-Median price;5-Typical price;6-Weighted Close)
extern int Length = 9; //Period of NonLagMA
extern int Displace = 0; //DispLace or Shift
extern double PctFilter = 0; //Dynamic filter in decimal
extern int Color = 0; //Switch of Color mode (1-color)
extern int ColorBarBack = 1; //Bar back for color mode
extern double Deviation = 0; //Up/down deviation
extern int AlertMode = 0; //Sound Alert switch (0-off,1-on)
extern int WarningMode = 0; //Sound Warning switch(0-off,1-on)
//---- indicator buffers
double MABuffer[];
double UpBuffer[];
double DnBuffer[];
double trend[];
double Del[];
double AvgDel[];
double alfa[];
int i, Phase, Len,Cycle=4;
double Coeff, beta, t, Sum, Weight, g;
double pi = 3.1415926535;
bool UpTrendAlert=false, DownTrendAlert=false;
//+------------------------------------------------------------------+
//| Custom indicator initialization function |
//+------------------------------------------------------------------+
int init()
{
IndicatorBuffers(6);
SetIndexStyle(0,DRAW_LINE);
SetIndexBuffer(0,MABuffer);
SetIndexStyle(1,DRAW_LINE);
SetIndexBuffer(1,UpBuffer);
SetIndexStyle(2,DRAW_LINE);
SetIndexBuffer(2,DnBuffer);
SetIndexBuffer(3,trend);
SetIndexBuffer(4,Del);
SetIndexBuffer(5,AvgDel);
string short_name;
//---- indicator line

IndicatorDigits(MarketInfo(Symbol(),MODE_DIGITS));
//---- name for DataWindow and indicator subwindow label
short_name="NonLagMA("+Length+")";
IndicatorShortName(short_name);
SetIndexLabel(0,"NonLagMA");
SetIndexLabel(1,"Up");
SetIndexLabel(2,"Dn");
//----
SetIndexShift(0,Displace);
SetIndexShift(1,Displace);
SetIndexShift(2,Displace);

SetIndexEmptyValue(0,EMPTY_VALUE);
SetIndexEmptyValue(1,EMPTY_VALUE);
SetIndexEmptyValue(2,EMPTY_VALUE);

SetIndexDrawBegin(0,Length*Cycle+Length+1);
SetIndexDrawBegin(1,Length*Cycle+Length+1);
SetIndexDrawBegin(2,Length*Cycle+Length+1);
//----

Coeff = 3*pi;
Phase = Length-1;
Len = Length*4 + Phase;
ArrayResize(alfa,Len);
Weight=0;

for (i=0;i<Len-1;i++)
{
if (i<=Phase-1) t = 1.0*i/(Phase-1);
else t = 1.0 + (i-Phase+1)*(2.0*Cycle-1.0)/(Cycle*Length-1.0);
beta = MathCos(pi*t);
g = 1.0/(Coeff*t+1);
if (t <= 0.5 ) g = 1;
alfa[i] = g * beta;
Weight += alfa[i];
}

return(0);
}
//+------------------------------------------------------------------+
//| NonLagMA_v7.1 |
//+------------------------------------------------------------------+
int start()
{
int i,shift, counted_bars=IndicatorCounted(),limit;
double price;
if ( counted_bars > 0 ) limit=Bars-counted_bars;
if ( counted_bars < 0 ) return(0);
if ( counted_bars ==0 ) limit=Bars-Len-1;
if ( counted_bars < 1 )

for(i=1;i<Length*Cycle+Length;i++)
{
MABuffer[Bars-i]=0;
UpBuffer[Bars-i]=0;
DnBuffer[Bars-i]=0;
}

for(shift=limit;shift>=0;shift--)
{
Sum = 0;
for (i=0;i<=Len-1;i++)
{
price = iMA(NULL,0,1,0,3,Price,i+shift);
Sum += alfa[i]*price;

}

if (Weight > 0) MABuffer[shift] = (1.0+Deviation/100)*Sum/Weight;


if (PctFilter>0)
{
Del[shift] = MathAbs(MABuffer[shift] - MABuffer[shift+1]);

double sumdel=0;
for (i=0;i<=Length-1;i++) sumdel = sumdel+Del[shift+i];
AvgDel[shift] = sumdel/Length;

double sumpow = 0;
for (i=0;i<=Length-1;i++) sumpow+=MathPow(Del[shift+i]-AvgDel[shift+i],2);
double StdDev = MathSqrt(sumpow/Length);

double Filter = PctFilter * StdDev;

if( MathAbs(MABuffer[shift]-MABuffer[shift+1]) < Filter ) MABuffer[shift]=MABuffer[shift+1];
}
else
Filter=0;

if (Color>0)
{
trend[shift]=trend[shift+1];
if (MABuffer[shift]-MABuffer[shift+1] > Filter) trend[shift]= 1;
if (MABuffer[shift+1]-MABuffer[shift] > Filter) trend[shift]=-1;
if (trend[shift]>0)
{
UpBuffer[shift] = MABuffer[shift];
if (trend[shift+ColorBarBack]<0) UpBuffer[shift+ColorBarBack]=MABuffer[shift+ColorBarBack];
DnBuffer[shift] = EMPTY_VALUE;
if (WarningMode>0 && trend[shift+1]<0 && shift==0) PlaySound("alert2.wav");
}
if (trend[shift]<0)
{
DnBuffer[shift] = MABuffer[shift];
if (trend[shift+ColorBarBack]>0) DnBuffer[shift+ColorBarBack]=MABuffer[shift+ColorBarBack];
UpBuffer[shift] = EMPTY_VALUE;
if (WarningMode>0 && trend[shift+1]>0 && shift==0) PlaySound("alert2.wav");
}
}
}
//----------
string Message;

if ( trend[2]<0 && trend[1]>0 && Volume[0]>1 && !UpTrendAlert)
{
Message = " "+Symbol()+" M"+Period()+": Signal for BUY";
if ( AlertMode>0 ) Alert (Message);
UpTrendAlert=true; DownTrendAlert=false;
}

if ( trend[2]>0 && trend[1]<0 && Volume[0]>1 && !DownTrendAlert)
{
Message = " "+Symbol()+" M"+Period()+": Signal for SELL";
if ( AlertMode>0 ) Alert (Message);
DownTrendAlert=true; UpTrendAlert=false;
}
//----
return(0);
}

Hi Codebreaker,

It looks like the pctFilter requires the faster moving average to be greater (or smaller than) than the slower moving average by a multiple (pctFilter) of the Standard Deviation of the difference between the 2 moving averages. If not, then it won't acknowledge an up or down trend.

So it filters out signals smaller than pctFilter * stdDev.

That's what it looks like anyway. Let me know if I read that incorrectly.

FYI,
Ngawang

Hi,

Sorry, I'm a Junior member, allegedly, so can't PM at all. .

I'm in Dublin and interested in created feeds for bookies/spreadbetting websites. Have done IGIndex, Lads etc. If you interested in some collaboration, please send me a PM.

Thanks.