forked from mia/Aegisub
86 lines
1.7 KiB
C++
86 lines
1.7 KiB
C++
// This file is part of FexGenericFilter and (C) 2006 by Hajo Krabbenhöft (tentacle)
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// All rights reserved but the aegisub project is allowed to use it.
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#include <math.h>
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#include "FexGenericFilter_Include.h"
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FexFilter::FexFilter()
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{
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Width = 3;
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}
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FexFilter::~FexFilter()
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{
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}
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double FexFilter::Filter( double t )
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{
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return t/Width;
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}
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/*
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f(x) = e^(-x^2 / (2 s^2) )
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f(x) = e^(-x^2 / t)
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width:
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SOLVE(0.1 = f(x), x, Real)
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x = - sqrt(t LN(10) ? x = sqrt(t LN(10)
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x = - 1.517427129·sqrt t ? x = 1.517427129·sqrt t
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x = - sqrt(2*s*s* LN(10)) ? x = sqrt(2*s*s* LN(10))
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x = - 2.145966026·s ? x = 2.145966026·s
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sum:
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Integral from -sqrt(t LN(10) to sqrt(t LN(10) of f(x) dx
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1.715955662·sqrt(t)
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2.426727768·s
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*/
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FexFilter_Gauss::FexFilter_Gauss( double sigma )
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{
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Sigma = sigma;
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TwoSigmaSq = 2*sigma*sigma;
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Width = 2.145966026 * sigma;
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Normalize = 1.0 / (2.426727768 * sigma);
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Normalize *= 1.0 + 0.1 / Width; //its the 0.1 we left out
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}
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FexFilter_Gauss::~FexFilter_Gauss()
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{
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}
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double FexFilter_Gauss::Filter( double t )
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{
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return exp( -t*t / TwoSigmaSq ) * Normalize;
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}
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/*
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f(x) = -x * e^(-x^2 / (2 s^2) )
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f(x) = -x * e^(-x^2 / t)
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width:
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use the width of gauss since i'm clueless here
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sum:
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Integral from -sqrt(t LN(10) to sqrt(t LN(10) of -x*f(x) dx
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0.7062351183·t^1.5
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*/
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FexFilter_GaussDerivation::FexFilter_GaussDerivation( double sigma )
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{
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Sigma = sigma;
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TwoSigmaSq = 2*sigma*sigma;
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Width = sqrt( TwoSigmaSq*log(10) );
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Normalize = 1.0 / (0.7062351183 * pow( TwoSigmaSq, 1.5 ));
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}
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FexFilter_GaussDerivation::~FexFilter_GaussDerivation()
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{
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}
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double FexFilter_GaussDerivation::Filter( double t )
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{
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return -t * exp( -t*t / TwoSigmaSq ) * Normalize;
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}
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