2D histogram

I am trying to plot a 2D histogram. I use 11 bins from 0 to 10 and 21 bins from -10 to 10. However when I plot the histogram it shows nothing in the first (or last bin). I attached the short program I use and the data file.
thank you very much for help
best regards
kaiser.C (787 Bytes)
kaiser.txt (1.93 KB)
cor_const.h (234 Bytes)

In your program you define kbins=200, not 20!
You should be careful with precision problems (in particular when reading a text file) and filling bins at the bin edges.
I suggest also to replace the line

TH2F *h = new TH2F("h","kaiser",kbins+1,-10,10,(kbins)/2. + 1,0,10); by

TH2F *h = new TH2F("h","kaiser",kbins,-10,10,(kbins)/2. ,0,10);