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SimpleFitting.C File Reference

Detailed Description

View in nbviewer Open in SWAN Create an exponential fitting The idea is to create a set of numbers x,y with the function x^3 and some noise from ROOT, fit the function to get the exponent (which must be near 3) and plot the points with noise, the known function and the fitted function

TCanvas *SimpleFitting(){
TCanvas *c1 = new TCanvas("c1","Curve Fitting",700,500);
// draw a frame to define the range
TMultiGraph *mg = new TMultiGraph();
// create the first plot (points with gaussian noise)
const Int_t n = 24;
Double_t y1[n] ;
//Generate the points along a X^3 with noise
TRandom rg;
for (Int_t i = 0; i < n; i++) {
x1[i] = rg.Uniform(0, 1);
y1[i] = TMath::Power(x1[i], 3) + rg.Gaus() * 0.06;
TGraph *gr1 = new TGraph(n,x1,y1);
// create the second plot
TF1 *f_known=new TF1("f_known","pow(x,3)",0,1);
TGraph *gr2 = new TGraph(f_known);
//passing data to Rfot fitting
r["x"]<<TVectorD(n, x1);
r["y"]<<TVectorD(n, y1);
//creating a R data frame
//fitting x and y to X^power using Nonlinear Least Squares
r<<"m <- nls(y ~ I(x^power),data = ds, start = list(power = 1),trace = T)";
//getting the exponent
Double_t power;
TF1 *f_fitted=new TF1("f_fitted","pow(x,[0])",0,1);
//plotting the fitted function
TGraph *gr3 = new TGraph(f_fitted);
//displaying basic results
TPaveText *pt = new TPaveText(0.1,0.6,0.5,0.9,"brNDC");
pt->AddText("Fitting x^power ");
pt->AddText(" \"Blue\" Points with gaussian noise to be fitted");
pt->AddText(" \"Red\" Known function x^3");
TString fmsg;
fmsg.Form(" \"Green\" Fitted function with power=%.4lf",power);
return c1;
ROOT::R::TRInterface & r
Definition Object.C:4
static const double x1[5]
int Int_t
Definition RtypesCore.h:45
double Double_t
Definition RtypesCore.h:59
@ kRed
Definition Rtypes.h:66
@ kGreen
Definition Rtypes.h:66
@ kBlue
Definition Rtypes.h:66
TVectorT< Double_t > TVectorD
Definition TVectorDfwd.h:23
ROOT R was implemented using the R Project library and the modules Rcpp and RInside
static TRInterface & Instance()
static method to get an TRInterface instance reference
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition TAttFill.h:37
virtual void SetMarkerColor(Color_t mcolor=1)
Set the marker color.
Definition TAttMarker.h:38
virtual void SetMarkerStyle(Style_t mstyle=1)
Set the marker style.
Definition TAttMarker.h:40
virtual void SetMarkerSize(Size_t msize=1)
Set the marker size.
Definition TAttMarker.h:41
virtual void SetTextAlign(Short_t align=11)
Set the text alignment.
Definition TAttText.h:41
The Canvas class.
Definition TCanvas.h:23
1-Dim function class
Definition TF1.h:213
virtual void SetParameter(Int_t param, Double_t value)
Definition TF1.h:634
A TGraph is an object made of two arrays X and Y with npoints each.
Definition TGraph.h:41
A TMultiGraph is a collection of TGraph (or derived) objects.
Definition TMultiGraph.h:36
virtual void Add(TGraph *graph, Option_t *chopt="")
Add a new graph to the list of graphs.
virtual void Draw(Option_t *chopt="")
Draw this multigraph with its current attributes.
A Pave (see TPave) with text, lines or/and boxes inside.
Definition TPaveText.h:21
virtual TText * AddText(Double_t x1, Double_t y1, const char *label)
Add a new Text line to this pavetext at given coordinates.
virtual void Draw(Option_t *option="")
Draw this pavetext with its current attributes.
This is the base class for the ROOT Random number generators.
Definition TRandom.h:27
virtual Double_t Gaus(Double_t mean=0, Double_t sigma=1)
Samples a random number from the standard Normal (Gaussian) Distribution with the given mean and sigm...
Definition TRandom.cxx:274
virtual void SetSeed(ULong_t seed=0)
Set the random generator seed.
Definition TRandom.cxx:608
virtual Double_t Uniform(Double_t x1=1)
Returns a uniform deviate on the interval (0, x1).
Definition TRandom.cxx:672
Basic string class.
Definition TString.h:136
void Form(const char *fmt,...)
Formats a string using a printf style format descriptor.
Definition TString.cxx:2309
TPaveText * pt
return c1
Definition legend1.C:41
const Int_t n
Definition legend1.C:16
LongDouble_t Power(LongDouble_t x, LongDouble_t y)
Definition TMath.h:735
Omar Zapata

Definition in file SimpleFitting.C.