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Reference Guide
Bessel.C File Reference

Detailed Description

View in nbviewer Open in SWAN Show the different kinds of Bessel functions available in ROOT To execute the macro type in:

root[0] .x Bessel.C
Definition: Bessel.py:1

It will create one canvas with the representation of the cylindrical and spherical Bessel functions regular and modified

#include "TMath.h"
#include "TF1.h"
#include "TCanvas.h"
#include <Riostream.h>
#include "TLegend.h"
#include "TLegendEntry.h"
#include "Math/IFunction.h"
#include <cmath>
#include "TSystem.h"
#include "TAxis.h"
#include "TPaveLabel.h"
void Bessel()
{
R__LOAD_LIBRARY(libMathMore);
TCanvas *DistCanvas = new TCanvas("DistCanvas", "Bessel functions example", 10, 10, 800, 600);
DistCanvas->SetFillColor(17);
DistCanvas->Divide(2, 2);
DistCanvas->cd(1);
gPad->SetGrid();
gPad->SetFrameFillColor(19);
TLegend *leg = new TLegend(0.75, 0.7, 0.89, 0.89);
int n = 5; //number of functions in each pad
//drawing the set of Bessel J functions
TF1* JBessel[5];
for(int nu = 0; nu < n; nu++)
{
JBessel[nu]= new TF1("J_0", "ROOT::Math::cyl_bessel_j([0],x)", 0, 10);
JBessel[nu]->SetParameters(nu, 0.0);
JBessel[nu]->SetTitle(""); //Bessel J functions");
JBessel[nu]->SetLineStyle(1);
JBessel[nu]->SetLineWidth(3);
JBessel[nu]->SetLineColor(nu+1);
}
JBessel[0]->TF1::GetXaxis()->SetTitle("x");
JBessel[0]->GetXaxis()->SetTitleSize(0.06);
JBessel[0]->GetXaxis()->SetTitleOffset(.7);
//setting the title in a label style
TPaveLabel *p1 = new TPaveLabel(.0,.90 , (.0+.50),(.90+.10) , "Bessel J functions", "NDC");
p1->SetFillColor(0);
p1->SetTextFont(22);
//setting the legend
leg->AddEntry(JBessel[0]->DrawCopy(), " J_0(x)", "l");
leg->AddEntry(JBessel[1]->DrawCopy("same"), " J_1(x)", "l");
leg->AddEntry(JBessel[2]->DrawCopy("same"), " J_2(x)", "l");
leg->AddEntry(JBessel[3]->DrawCopy("same"), " J_3(x)", "l");
leg->AddEntry(JBessel[4]->DrawCopy("same"), " J_4(x)", "l");
leg->Draw();
p1->Draw();
//------------------------------------------------
DistCanvas->cd(2);
gPad->SetGrid();
gPad->SetFrameFillColor(19);
TLegend *leg2 = new TLegend(0.75, 0.7, 0.89, 0.89);
//------------------------------------------------
//Drawing Bessel k
TF1* KBessel[5];
for(int nu = 0; nu < n; nu++){
KBessel[nu]= new TF1("J_0", "ROOT::Math::cyl_bessel_k([0],x)", 0, 10);
KBessel[nu]->SetParameters(nu, 0.0);
KBessel[nu]->SetTitle("Bessel K functions");
KBessel[nu]->SetLineStyle(1);
KBessel[nu]->SetLineWidth(3);
KBessel[nu]->SetLineColor(nu+1);
}
KBessel[0]->GetXaxis()->SetTitle("x");
KBessel[0]->GetXaxis()->SetTitleSize(0.06);
KBessel[0]->GetXaxis()->SetTitleOffset(.7);
//setting title
TPaveLabel *p2 = new TPaveLabel(.0,.90 , (.0+.50),(.90+.10) , "Bessel K functions", "NDC");
p2->SetFillColor(0);
p2->SetTextFont(22);
//setting legend
leg2->AddEntry(KBessel[0]->DrawCopy(), " K_0(x)", "l");
leg2->AddEntry(KBessel[1]->DrawCopy("same"), " K_1(x)", "l");
leg2->AddEntry(KBessel[2]->DrawCopy("same"), " K_2(x)", "l");
leg2->AddEntry(KBessel[3]->DrawCopy("same"), " K_3(x)", "l");
leg2->AddEntry(KBessel[4]->DrawCopy("same"), " K_4(x)", "l");
leg2->Draw();
p2->Draw();
//------------------------------------------------
DistCanvas->cd(3);
gPad->SetGrid();
gPad->SetFrameFillColor(19);
TLegend *leg3 = new TLegend(0.75, 0.7, 0.89, 0.89);
//------------------------------------------------
//Drawing Bessel i
TF1* iBessel[5];
for(int nu = 0; nu <= 4; nu++){
iBessel[nu]= new TF1("J_0", "ROOT::Math::cyl_bessel_i([0],x)", 0, 10);
iBessel[nu]->SetParameters(nu, 0.0);
iBessel[nu]->SetTitle("Bessel I functions");
iBessel[nu]->SetLineStyle(1);
iBessel[nu]->SetLineWidth(3);
iBessel[nu]->SetLineColor(nu+1);
}
iBessel[0]->GetXaxis()->SetTitle("x");
iBessel[0]->GetXaxis()->SetTitleSize(0.06);
iBessel[0]->GetXaxis()->SetTitleOffset(.7);
//setting title
TPaveLabel *p3 = new TPaveLabel(.0,.90 , (.0+.50),(.90+.10) ,"Bessel I functions", "NDC");
p3->SetFillColor(0);
p3->SetTextFont(22);
//setting legend
leg3->AddEntry(iBessel[0]->DrawCopy(), " I_0", "l");
leg3->AddEntry(iBessel[1]->DrawCopy("same"), " I_1(x)", "l");
leg3->AddEntry(iBessel[2]->DrawCopy("same"), " I_2(x)", "l");
leg3->AddEntry(iBessel[3]->DrawCopy("same"), " I_3(x)", "l");
leg3->AddEntry(iBessel[4]->DrawCopy("same"), " I_4(x)", "l");
leg3->Draw();
p3->Draw();
//------------------------------------------------
DistCanvas->cd(4);
gPad->SetGrid();
gPad->SetFrameFillColor(19);
TLegend *leg4 = new TLegend(0.75, 0.7, 0.89, 0.89);
//------------------------------------------------
//Drawing sph_bessel
TF1* jBessel[5];
for(int nu = 0; nu <= 4; nu++){
jBessel[nu]= new TF1("J_0", "ROOT::Math::sph_bessel([0],x)", 0, 10);
jBessel[nu]->SetParameters(nu, 0.0);
jBessel[nu]->SetTitle("Bessel j functions");
jBessel[nu]->SetLineStyle(1);
jBessel[nu]->SetLineWidth(3);
jBessel[nu]->SetLineColor(nu+1);
}
jBessel[0]->GetXaxis()->SetTitle("x");
jBessel[0]->GetXaxis()->SetTitleSize(0.06);
jBessel[0]->GetXaxis()->SetTitleOffset(.7);
//setting title
TPaveLabel *p4 = new TPaveLabel(.0,.90 , (.0+.50),(.90+.10) ,"Bessel j functions", "NDC");
p4->SetFillColor(0);
p4->SetTextFont(22);
//setting legend
leg4->AddEntry(jBessel[0]->DrawCopy(), " j_0(x)", "l");
leg4->AddEntry(jBessel[1]->DrawCopy("same"), " j_1(x)", "l");
leg4->AddEntry(jBessel[2]->DrawCopy("same"), " j_2(x)", "l");
leg4->AddEntry(jBessel[3]->DrawCopy("same"), " j_3(x)", "l");
leg4->AddEntry(jBessel[4]->DrawCopy("same"), " j_4(x)", "l");
leg4->Draw();
p4->Draw();
DistCanvas->cd();
}
#define R__LOAD_LIBRARY(LIBRARY)
Definition: Rtypes.h:489
@ kBlack
Definition: Rtypes.h:65
#define gPad
Definition: TVirtualPad.h:288
virtual void SetTitleOffset(Float_t offset=1)
Set distance between the axis and the axis title.
Definition: TAttAxis.cxx:301
virtual void SetTitleSize(Float_t size=0.04)
Set size of axis title.
Definition: TAttAxis.cxx:312
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition: TAttFill.h:37
virtual void SetLineStyle(Style_t lstyle)
Set the line style.
Definition: TAttLine.h:42
virtual void SetLineWidth(Width_t lwidth)
Set the line width.
Definition: TAttLine.h:43
virtual void SetLineColor(Color_t lcolor)
Set the line color.
Definition: TAttLine.h:40
virtual void SetTextColor(Color_t tcolor=1)
Set the text color.
Definition: TAttText.h:44
virtual void SetTextFont(Font_t tfont=62)
Set the text font.
Definition: TAttText.h:46
The Canvas class.
Definition: TCanvas.h:23
TVirtualPad * cd(Int_t subpadnumber=0) override
Set current canvas & pad.
Definition: TCanvas.cxx:706
1-Dim function class
Definition: TF1.h:213
void SetTitle(const char *title="") override
Set function title if title has the form "fffffff;xxxx;yyyy", it is assumed that the function title i...
Definition: TF1.cxx:3600
virtual void SetParameters(const Double_t *params)
Definition: TF1.h:649
TAxis * GetXaxis() const
Get x axis of the function.
Definition: TF1.cxx:2418
This class displays a legend box (TPaveText) containing several legend entries.
Definition: TLegend.h:23
TLegendEntry * AddEntry(const TObject *obj, const char *label="", Option_t *option="lpf")
Add a new entry to this legend.
Definition: TLegend.cxx:317
void Draw(Option_t *option="") override
Draw this legend with its current attributes.
Definition: TLegend.cxx:422
virtual void SetTitle(const char *title="")
Set the title of the TNamed.
Definition: TNamed.cxx:164
void Divide(Int_t nx=1, Int_t ny=1, Float_t xmargin=0.01, Float_t ymargin=0.01, Int_t color=0) override
Automatic pad generation by division.
Definition: TPad.cxx:1152
A Pave (see TPave) with a text centered in the Pave.
Definition: TPaveLabel.h:20
void Draw(Option_t *option="") override
Draw this pavelabel with its current attributes.
Definition: TPaveLabel.cxx:87
const Int_t n
Definition: legend1.C:16
leg
Definition: legend1.C:34
Author
Magdalena Slawinska

Definition in file Bessel.C.