GetTime

ROOT
1

Hi,
I’m new with Root. I’m also dumb when it comes to C++, so I need some help, please
I would like to check time that root takes to perform some commands. I guess it is something like gRoot->GetTime() or gSystem->GetTime() (which one?), but before that some library needs to be loaded (does it?) and I have no idea which…
Can somebody give me a hint about that, please?

2

Hi Julia,
you want a TStopwatch. See e.g. $ROOTSYS/tutorials/testrandom.C
Axel.

3

Thanx Axel,
I thought more about loading something in Root command line than adding it to the script. SOmething like gSystem->Load(herethe properlibraryIguess) and then before I run something in root I would perform this gSystem->GetTime() and after that something finishes root gives me time in secons it took to do it… Any ideas?
Cheers,

4

Julia,

At the ROOT command line, do
gROOT->Time();

then all subsequent commands will be timed (real and cpu time)

Rene

5

Hi Julia,

you can do
root [0] {TH1F h(“h”,“h”,10,0.,1.); TStopwatch sw; sw.Start(); h.FillRandom(“gaus”, 10000); std::cout<<sw.CpuTime();}

Here, TH1F::FillRandom is the command that’s being timed. You can also run a macro by using
root [0] {TStopwatch sw; sw.Start(); gROOT->ProcessLine(".x MyMacro.C"); std::cout<<sw.CpuTime();}

Axel.