# Zero Lag EMA (Using an Error Correcting Filter)
# Mobius
# Ported to TOS 08.31.2016 from Article by John Ehlers
# Using an EMA error term, the current price ? EMA[1], the amplitude of the error term is altered by multiplying the error by a gain term. The new filter is an EC or Error Corrected EMA.

# Inputs:
input Length = 20;
input GainLimit = 50;
input LabelsOn = yes;

# Vars:
def alpha;
def BestGain;
def EC1;
def Gain;
def EC;
def Error;
def LeastError;
def EMA;
alpha = 2 / (Length + 1);
EMA = alpha * close + (1 - alpha) * EMA[1];
plot EMAdata = EMA;
EMAdata.SetDefaultColor(Color.Yellow);
Gain = fold g = -GainLimit to GainLimit
       do getValue(g / 10, g);
EC1 = fold V = -GainLimit to GainLimit
      do alpha * (EMA + (fold i = -GainLimit to GainLimit
                         do i / 10) * (Close - EC1[1])) + (1 - alpha) * EC1[1];
Error = AbsValue(Close - EC1);
If Error < 1000000
Then {
LeastError = Error;
BestGain = Gain;
} else {
LeastError = LeastError[1];
BestGain = 0;
}
EC = alpha * (EMA + BestGain * (Close - EC1)) + (1 - alpha) * EC1;
Plot ECdata = EC;
ECdata.SetDefaultColor(Color.Cyan);
AddLabel(LabelsOn, "Standard EMA", color.yellow);
AddLabel(LabelsOn, "Error Corrected EMA", color.cyan);
#End Code Error Corrected EMA