root-6.10.00/html/waves_8C.html

#include "TROOT.h"

#include "TCanvas.h"

#include "TColor.h"

#include "TArc.h"

#include "TGraph.h"

#include "TF2.h"

#include "TLine.h"

#include "TLatex.h"

#include "TMath.h"

#include "TStyle.h"

#include "Riostream.h"


TF2 * finter;


//______________________________________________________________

Double_t interference( Double_t *x, Double_t *par)

{

   Double_t x_p2 = x[0] * x[0];

   Double_t d_2 = 0.5 * par[2];

   Double_t ym_p2 = (x[1] - d_2) * (x[1] - d_2);

   Double_t yp_p2 = (x[1] + d_2) * (x[1] + d_2);

   Double_t  tpi_l = TMath::Pi() /  par[1];

   Double_t amplitude = par[0] * (cos(tpi_l  * sqrt(x_p2 + ym_p2))

                      + par[3] * cos(tpi_l  * sqrt(x_p2 + yp_p2)));

   return amplitude * amplitude;

}


//_____________________________________________________________

Double_t result( Double_t *x, Double_t *par)

{

   Double_t xint[2];

   Double_t  maxintens = 0, xcur = 14;

   Double_t dlambda = 0.1 * par[1];

   for(Int_t i=0; i<10; i++){

      xint[0] = xcur;

      xint[1] = x[1];

      Double_t  intens = interference(xint, par);

      if(intens > maxintens) maxintens = intens;

      xcur -= dlambda;

   }

   return maxintens;

}


//_____________________________________________________________

void waves( Double_t d = 3, Double_t lambda = 1, Double_t amp = 10)

{

   TCanvas *c1 = new TCanvas("waves", "A double slit experiment",

      300,40, 1004, 759);

   c1->Range(0, -10,  30, 10);

   c1->SetFillColor(0);

   TPad *pad = new TPad("pr","pr",  0.5, 0 , 1., 1);

   pad->Range(0, -10,  15, 10);

   pad->Draw();


   const Int_t colNum = 30;

   Int_t palette[colNum];

   for (Int_t i=0;i<colNum;i++) {

      TColor *color = new TColor(1001+i

      ,    pow(i/((colNum)*1.0),0.3)

      ,    pow(i/((colNum)*1.0),0.3)

      ,0.5*(i/((colNum)*1.0)),"");

      palette[i] = 1001+i;

   }

   gStyle->SetPalette(colNum,palette);

   c1->cd();

   TF2 * f0 = new TF2("ray_source",interference, 0.02, 15, -8, 8, 4);


   f0->SetParameters(amp, lambda, 0, 0);

   f0->SetNpx(200);

   f0->SetNpy(200);

   f0->SetContour(colNum-2);

   f0->Draw("samecolz");


   TLatex title;

   title.DrawLatex(1.6, 8.5, "A double slit experiment");


   TGraph *graph = new TGraph(4);

   graph->SetFillColor(0);

   graph->SetFillStyle(1001);

   graph->SetLineWidth(0);

   graph->SetPoint(0, 0., 0.1);

   graph->SetPoint(1, 14.8, 8);

   graph->SetPoint(2, 0, 8);

   graph->SetPoint(3, 0, 0.1);

   graph->Draw("F");


   graph = new TGraph(4);

   graph->SetFillColor(0);

   graph->SetFillStyle(1001);

   graph->SetLineWidth(0);

   graph->SetPoint(0, 0, -0.1);

   graph->SetPoint(1, 14.8, -8);

   graph->SetPoint(2, 0, -8);

   graph->SetPoint(3, 0, -0.1);

   graph->Draw("F");


   TLine * line;

   line = new TLine(15,-10, 15, 0 - 0.5*d -0.2);

   line->SetLineWidth(10); line->Draw();

   line = new TLine(15, 0 - 0.5*d +0.2 ,15, 0 + 0.5*d -0.2);

   line->SetLineWidth(10); line->Draw();


   line = new TLine(15,0 + 0.5*d + 0.2,15, 10);

   line->SetLineWidth(10); line->Draw();


   pad ->cd();

   finter = new TF2("interference",interference, 0.01, 14, -10, 10, 4);


   finter->SetParameters(amp, lambda, d, 1);

   finter->SetNpx(200);

   finter->SetNpy(200);

   finter->SetContour(colNum-2);

   finter->Draw("samecolorz");


   TArc *arc = new TArc();;

   arc->SetFillStyle(0);

   arc->SetLineWidth(2);

   arc->SetLineColor(5);

   Float_t r = 0.5 * lambda, dr = lambda;

   for (Int_t i = 0; i < 16; i++) {

      arc->DrawArc(0,  0.5*d, r, 0., 360., "only");

      arc->DrawArc(0, -0.5*d, r, 0., 360., "only");

      r += dr;

   }


   pad ->cd();

   TF2 * fresult = new TF2("result",result, 14, 15, -10, 10, 4);


   fresult->SetParameters(amp, lambda, d, 1);

   fresult->SetNpx(300);

   fresult->SetNpy(300);

   fresult->SetContour(colNum-2);

   fresult->Draw("samecolor");

   line = new TLine(13.8,-10, 14, 10);

   line->SetLineWidth(10); line->SetLineColor(0); line->Draw();

   c1->Modified(kTRUE);

   c1->Update();

   c1->SetEditable(kTRUE);

}