I am asking a pretty basic question but I couldn’t figure out how to do myself.
I have a tree and there are several branches in it like storage time, wavelength, time of flight etc.
I want to draw a histogram of branch “storage time” with filter on “wavelength” and this wavelength is a variable. So, in principle I want to draw array of histogram in a loop on same pad with changing wavelength (wavelength starts from 500 nm and changes in steps on 10nm.)
Thank you for quick help. This time I checked my code carefully with the corrections of typos…
and succeeded in drawing histogram but it draws only for j== 0. and same error message pops up.