TH1 and strange BinWidth

[meyerma]

Hello,

I am facing a strange issue… After having created 2 histograms
I saved them in a root file (attached)

Then when I load them and I try this :

cout << h->GetXaxis()->GetBinWidth(1) << " " << h0->GetXaxis()->GetBinWidth(1) << endl;
h->GetXaxis()->GetBinWidth(1) == h0->GetXaxis()->GetBinWidth(1)

I am getting this output :

0.04 0.04
0

I do not understand what it going on with those histograms and what I did wrong… Some help ?

Thank you very much !
output.root (79.4 KB)

[meyerma]

Please use

_file0->Get(“test”);
_file0->Get(“test2”);

[Wile_E_Coyote]

root [1] test->GetXaxis()->GetBinWidth(1) - test2->GetXaxis()->GetBinWidth(1)
(const double)1.38777878078144568e-17

See also:

ROOT rounds to Integers

There is NO " >>exact<< Double_t". This is a “Floating point” value in a “Double-precision floating-point format”. See especially “Floating point - Representable numbers, conversion and rounding”. If you "#include ", both “strtod” and “atof” return a “double” value: double strtod(const char *nptr, char **endptr); double atof(const char *nptr); (See “man strtod” and “man atof”.) BTW. In your “ReadData.C”, you are missing something like “Double_t val;” (and “continue;// exit if file not foun…