void stddev() {
   gStyle->SetPadTickX(1);
   gStyle->SetPadTickY(1);
   gStyle->SetOptFit(1111);
   gPad->Modified();
   c1 = new TCanvas("c1","stddev vs B",200,10,900,900);
   c1->SetFillColor(10);
   c1->SetGrid();
   c1->GetFrame()->SetFillColor(21);
   c1->GetFrame()->SetBorderSize(15);
   c1->Divide(2,2);
  
   const Int_t n = 20;
   const Int_t m= 12;
   Double_t B_0[n] = {0,0,0.1,0.1,0.2,0.2,0.2,0.3,0.3,0.4,0.4,0.5,0.5,0.5,0.5,0.8,1.,1.,1.,1.2};
   Double_t sigma_B_0[n]  = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
   Double_t stddev_0 [n] = {169581.2304,526752.0141,383491.1805,328376.0654,568675.6094,361794.3011,364649.7216,260764.2881,265567.8979,292765.3066,294659.8121,236866.2946,128819.3522,328433.025,195081.6169,196760.1693,282988.4622,131674.6421,273087.4508,59547.78323};
   Double_t sigma_stddev_0[n]  = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
   Double_t ratio_0 [n] = {4.259388629,13.86121202,3.509834296,2.01691486,4.446722972,1.939848732,2.807042105,2.00486833,1.436617048,1.707738992,2.479423374,2.366865081,0.858081506,3.384836512,2.011776427,6.077426774,57.88631332,17.44770691,18.10749348,87.18341585};
   Double_t sigma_ratio_0 [n] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
   Double_t B_10 [m] = {0,0,0.2,0.2,0.5,0.5,0.5,0.8,0.8,1.,1.,1.2};
   Double_t sigma_B_10 [m] = {0,0,0,0,0,0,0,0,0,0,0,0};
   Double_t stddev_10 [m] ={797591.547,792268.45,311174.5896,372017.5437,239356.4564,195926.2151,89034.36957,97007.56171,141983.7567,177860.3267,235467.0191,54715.42994};
   Double_t sigma_stddev_10 [m]={0,0,0,0,0,0,0,0,0,0,0,0};
   Double_t ratio_10 [m] ={21.85084227,25.15717474,2.304002646,2.714083863,2.580132982,2.139222316,0.641863493,3.959396021,5.733590319,22.17823738,31.88587272,150.5008124};
   Double_t sigma_ratio_10 [m] = {0,0,0,0,0,0,0,0,0,0,0,0};
   
   //graph setup
   TGraphErrors *gr1 = new TGraphErrors(n,B_0,stddev_0,sigma_B_0,sigma_stddev_0);
   gr1->SetTitle("Stddev vs B, #theta=0#circ");
   gr1->SetMarkerColor(4);
   gr1->SetMarkerStyle(21);
   gr1->GetXaxis()->SetLimits(0.,1.4);
   c1->cd(1);
   c1->cd(1)->SetLogy();
   gr1->SetMaximum(10000000);
   gr1->SetMinimum(9900);
   gPad->SetLeftMargin(.17);
   gr1->Draw("AP");

   gr1->GetXaxis()->SetTitle("B (T)");
   gr1->GetYaxis()->SetTitle("Stddev");
   gr1->GetXaxis()->CenterTitle(true);
   gr1->GetYaxis()->CenterTitle(true);
   gr1->GetYaxis()->SetTitleOffset(1.5);
   gr1->GetXaxis()->SetTitleSize(0.046);
   gr1->GetYaxis()->SetTitleSize(0.046);
   gr1->GetXaxis()->SetLabelSize(0.04);
   gr1->GetYaxis()->SetLabelSize(0.04);
   
   TGraphErrors *gr2 = new TGraphErrors(m,B_10,stddev_10,sigma_B_10,sigma_stddev_10);
   gr2->SetTitle("Stddev vs B, #theta=10#circ");
   gr2->SetMarkerColor(4);
   gr2->SetMarkerStyle(21);
   gr2->GetXaxis()->SetLimits(0,1.4);
   c1->cd(2);
   c1->cd(2)->SetLogy();
   gr2->SetMaximum(10000000);
   gr2->SetMinimum(9900);
   gPad->SetLeftMargin(.17);
   gr2->Draw("AP");
   

   gr2->GetXaxis()->SetTitle("B (T)");
   gr2->GetYaxis()->SetTitle("Stddev");
   gr2->GetXaxis()->CenterTitle(true);
   gr2->GetYaxis()->CenterTitle(true);
   gr2->GetYaxis()->SetTitleOffset(1.5);
   gr2->GetXaxis()->SetTitleSize(0.046);
   gr2->GetYaxis()->SetTitleSize(0.046);
   gr2->GetXaxis()->SetLabelSize(0.04);
   gr2->GetYaxis()->SetLabelSize(0.04);
   
   TGraphErrors *gr3 = new TGraphErrors(n,B_0,ratio_0,sigma_B_0,sigma_ratio_0);
   gr3->SetTitle("Stddev/Mean vs B, #theta=0#circ");
   gr3->SetMarkerColor(4);
   gr3->SetMarkerStyle(21);
   gr3->GetXaxis()->SetLimits(0,1.4);
   c1->cd(3);
   gr3->SetMaximum(100);
   gr3->SetMinimum(-2);
   gPad->SetLeftMargin(.17);
   gr3->Draw("AP");
   

   gr3->GetXaxis()->SetTitle("B (T)");
   gr3->GetYaxis()->SetTitle("Stddev/Mean (%)");
   gr3->GetXaxis()->CenterTitle(true);
   gr3->GetYaxis()->CenterTitle(true);
   gr3->GetXaxis()->SetTitleSize(0.046);
   gr3->GetYaxis()->SetTitleSize(0.046);
   gr3->GetXaxis()->SetLabelSize(0.04);
   gr3->GetYaxis()->SetLabelSize(0.04);
   
   TGraphErrors *gr4 = new TGraphErrors(m,B_10,ratio_10,sigma_B_10,sigma_ratio_10);
   gr4->SetTitle("Stddev/Mean vs B, #theta=10#circ");
   gr4->SetMarkerColor(4);
   gr4->SetMarkerStyle(21);
   gr4->GetXaxis()->SetLimits(0,1.4);
   c1->cd(4);
   gr4->SetMaximum(200);
   gr4->SetMinimum(-2);
   gPad->SetLeftMargin(.17);
   gr4->Draw("AP");
   

   gr4->GetXaxis()->SetTitle("B (T)");
   gr4->GetYaxis()->SetTitle("Stddev/Mean (%)");
   gr4->GetXaxis()->CenterTitle(true);
   gr4->GetYaxis()->CenterTitle(true);
   gr4->GetXaxis()->SetTitleSize(0.046);
   gr4->GetYaxis()->SetTitleSize(0.046);
   gr4->GetXaxis()->SetLabelSize(0.04);
   gr4->GetYaxis()->SetLabelSize(0.04);

   
}
   //gr1 = new TGraphErrors(n,x,y,ex,ey);