Any C++ guru want to optimize TH1::Fill() to make it fast?

ROOT
1

I looked at TH1::Fill() function and

It is just so much faster to fill arrays than histograms …

most of the time for me at least, only 3 operations needed:

(MAX - MIN) / binWidth

before incrementing content by one.

but it seems like a lot of stuff going on for every fill, which slows things down. Anyone interested in making it faster?

Perhaps updating auxiliary variables once in a while, or only when accessed ?

Or have TH1F_SimpleFixedBin wich does not have all bells and whistles
but is truely fast.

Similar to TGraph and TGraphErrors

P.S. FillBuffer is not an option since memory is not unlimited.

2

Just calculate bin values yourself and use SetBinContent :slight_smile:) I gues it’ll be faster :slight_smile:)

3

I already replied to you in a separate mail.
If you can improve the fill operations by more than 10 per cent without introducing side effects, let me know, I will introduce your code.

And please send a piece of ruuning code illustrating the Fill performance penalty.

Rene