private RawSpectrum ExponentialFitting(RawSpectrum spectrum)
{
int n = spectrum.mAbsoluteIntensities.Count;
var x = spectrum.mWavelengths;
var y = spectrum.mAbsoluteIntensities;
double xsum = 0, x2sum = 0, ysum = 0, xysum = 0;
for (int i = 0; i < n; ++i)
{
if (y[i] > 0)
{
double lny = Math.Log(y[i]);
xsum += x[i];
ysum += lny;
x2sum += x[i] * x[i];
xysum += x[i] * lny;
}
}
double a = (n * xysum - xsum * ysum) / (n * x2sum - xsum * xsum);
double b = (x2sum * ysum - xsum * xysum) / (x2sum * n - xsum * xsum);
double c = Math.Exp(b);
var fittingCurve = new RawSpectrum();
for (int i = 0; i < n; ++i)
{
fittingCurve.mWavelengths.Add(x[i]);
fittingCurve.mAbsoluteIntensities.Add(c * Math.Exp(a * x[i]));
}
return(fittingCurve);
}
void PlotFourierTransform(RawSpectrum spec, int n, string name)
{
var series = chrFourierTransform.Series.Add(name);
series.ChartType = SeriesChartType.FastLine;
for (int i = 0; i < spec.mAbsoluteIntensities.Count; ++i)
{
series.Points.AddXY(Math.Round(spec.mWavelengths[i], 2), spec.mAbsoluteIntensities[i]);
}
}
void PlotSpline(RawSpectrum spec, int n)
{
var name = "Spline " + n;
var series = chrMainChart.Series.Add(name);
series.ChartType = SeriesChartType.FastLine;
for (int i = 0; i < spec.mAbsoluteIntensities.Count; ++i)
{
series.Points.AddXY(Math.Round(spec.mWavelengths[i], 2), spec.mAbsoluteIntensities[i]);
}
}
private void btnCalculate_Click(object sender, EventArgs e)
{
double ka = (double)nudFWHM.Value;
// remove all computed curves
mDeconvolutedSpectra.Clear();
mFourierTransforms.Clear();
mModifiedFourierTransforms.Clear();
mFittingCurves.Clear();
foreach (var experimentalSpectrum in mSpectra)
{
// define cutoff position using narrowing factor
int cutoffPosition = (int)(experimentalSpectrum.mAbsoluteIntensities.Value.Length / (double)nudNarrowingFactor.Value);
// absolute intensities alias
var spectrum = experimentalSpectrum.mAbsoluteIntensities.Value;
// copy spectrum absolute intensities into array of complex numbers
Complex[] cdata = new Complex[spectrum.Length];
for (int i = 0; i < spectrum.Length; ++i)
{
cdata[i] = spectrum[i];
}
// do inverse fourier transform to go to time domain
FourierTransform.DFT(cdata, FourierTransform.Direction.Backward);
// add inverse fourier transform plot to the fourier chart
var fourierTransform = new RawSpectrum();
for (int i = 0; i < spectrum.Length; ++i)
{
fourierTransform.mAbsoluteIntensities.Add(cdata[i].Real);
fourierTransform.mWavelengths.Add(i);
}
mFourierTransforms.Add(fourierTransform);
// deconvolve exponential decay
for (int i = 0; i < spectrum.Length; ++i)
{
cdata[i] /= ExponentialDeconvolution(cutoffPosition * ka, i);
}
// apply apodization function
double constantScaler = 2.0f;
for (int i = 0; i < spectrum.Length; ++i)
{
double a = Apodization(cutoffPosition, i);
cdata[i] *= a * a * constantScaler;
}
// add modified fourier transform plot to the fourier chart
var modifiedFourierTransform = new RawSpectrum();
for (int i = 0; i < spectrum.Length; ++i)
{
modifiedFourierTransform.mAbsoluteIntensities.Add(cdata[i].Real);
modifiedFourierTransform.mWavelengths.Add(i);
}
mModifiedFourierTransforms.Add(modifiedFourierTransform);
// do forward fourier transform to go back to frequency domain
FourierTransform.DFT(cdata, FourierTransform.Direction.Forward);
// add deconvolved spectrum to the chart
var deconvolution = new RawSpectrum();
for (int i = 0; i < spectrum.Length; ++i)
{
deconvolution.mAbsoluteIntensities.Add(cdata[i].Real);
deconvolution.mWavelengths.Add(experimentalSpectrum.mWaveLengths.Value[i]);
}
mDeconvolutedSpectra.Add(deconvolution);
}
UpdateChart();
}