Log x axis ticks

[ferhue]

Hello, I was wondering if there is a trick to add more ticks (as well as label and gridlines) at 1100, 1200, 1300, etc in the image below. The right area of the plot doesn’t look optimum, and I cannot figure out how to change it.

    TCanvas* c = new TCanvas();
    c->SetGridx();
    c->SetGridy();
    c->SetLogx();
    c->SetLogy();
    TF1* f = new TF1("f", "1.73E-13*pow(x, 5.775)", 699, 1701);
    f->GetHistogram()->GetXaxis()->SetMoreLogLabels();
    f->GetHistogram()->GetXaxis()->SetNoExponent();
    f->Draw("");

Thanks in advance.

[couet]

No, the next tick in log scale will be 2000

[ferhue]

Thanks. Is there a way to manually add custom ticks and labels on top? Maybe with TLines?

Or is there a way to add secondary tick marks or line inbetween the current ones?

[dastudillo]

Based on this solution

Draw X-Axis with specific values

This is a slight modification of a macro found on this forum some time ago, so all credit goes to the original author, couet: void aa() { TGraph *g1 = new TGraph("aa.txt"); g1->SetMarkerStyle(20); g1->SetMarkerColorAlpha(kBlue, 0.35); g1->GetYaxis()->SetTitle("Y axis"); g1->GetXaxis()->SetTitle("X axis"); g1->SetMarkerSize(1); g1->Draw("APL"); g1->GetXaxis()->SetLabelSize(0); g1->GetXaxis()->SetTickLength(0); Int_t i,n; Double_t x,y; TLatex *t; TLine *tick; TLine *…

You could do something like:

{
TCanvas* c = new TCanvas();
c->SetGridx();
c->SetGridy();
c->SetLogx();
c->SetLogy();
TLatex *t;
TLine *tick;
TF1* f = new TF1("f", "1.73E-13*pow(x, 5.775)", 699, 1701);
f->GetHistogram()->GetXaxis()->SetMoreLogLabels();
f->GetHistogram()->GetXaxis()->SetNoExponent();
f->Draw();
double ymin = f->GetHistogram()->GetMinimum();
double ymax = f->GetHistogram()->GetMaximum();
double dy = (ymax-ymin);
cout << "ymin/max " << ymin << " / " << ymax << endl;
for (int i=1; i<f->GetHistogram()->GetXaxis()->GetNbins();++i) {
  double x = f->GetHistogram()->GetXaxis()->GetBinCenter(i);
  double xL = f->GetHistogram()->GetXaxis()->GetBinLowEdge(i);
  double xU = f->GetHistogram()->GetXaxis()->GetBinUpEdge(i);
  if (xL<=1200 && xU>1200) {
    t = new TLatex(x, 3770, Form("%d",1200));
    t->SetTextSize(0.035);
    t->SetTextFont(42);
    t->SetTextAlign(21);
    t->Draw();
    tick = new TLine(x,ymin,x,ymin+0.0008*dy);
    tick->Draw();
  }
}

where I determined the y of the TLatex (3770) and the factor for dy (0.0008) by trial and error, but you might find formulas for your case. From this you can surely figure out the vertical grid lines.