> Hi George, > > The efficiency issue (TArrayD vs. Double_t *) will be resolved quickly later > this week by some profiling. I do remember from similar checks that > the difference was noticable, in particular the boundary checking. Anyhow, > I will try to get more quantitative. If you use operator[] or At() in the inner loop, you could definitely see something, particularly in a less-optimized compilation mode (a good optimizer will probably be able to observe that the value of size is not changing in the loop and do the check only once or twice at the edge conditions). I note that while ROOT does not provide the equivalent of an UncheckedAt() function for the TArrayD (would probably be a nice addition), it's not all THAT hard to evade the checks, since TArrayD does give you unfettered access to its internals with GetArray() (1). So if you need efficiency in your inner loop, just grab the array afterwards and index off that. (1) Could ROOT at least change the overloading of this operator so that GetArray() const returns a const Double_t *, not a Double_t *, as well as having Double_t * GetArray()? George Heintzelman gah@bnl.gov
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