TAxis FixedToVariable and VariableToFixed proposal

[ksmith]

Was @moneta able to comment on this? A similar question was asked:

TAxis::GetXbins does not always return bin edges

Hi, I am attempting to build a 2D histogram with bins defined in 1D histograms, but it appears that the TAxis::GetXbins function does not always produce an array of bin edges. For the case where a user provides the number of bins and min and max, the edge array is not produced. In the case where an array of edges is passed GetXbins works as expected. This makes generalized code that can read from either type of histogram much more difficult. Below is an example where the wrong bin edges are pro…