larsmans/scipy — comment on commit ebb2e71915ff3644bd55dcb010d06a0197ee2bad
File: scipy/misc/common.py line 47
By charris:

OK, I can see that roundoff error would be a problem since the *.reduce version does a lot more conversions between the two representations. I benchmarked the implementation here back when and it was also faster for the same reason. Hmm... now that I think about it, the numpy loops can detect the reduce method and I don't see why this double pass approach couldn't be made to work there...