> > I would go to the natural type we get when building the exception. If we may > build the exception from both types, then I would select RealVector. We do > not intend to perform large processing on elements, but we want to display > them and I think we do have formatting for vectors. > > best regards, > Luc
I actually was not thinking of speed for --as you mentioned-- exceptional cases, but rather to ease of debugging. If several vectors could have caused the exception, it's easier to identify the right one if we have a reference rather than a deep copy (overwise all the components must be tested). Speaking of speed, I do have a performance issue, which I stated this morning in MATH-581, but maybe it would be better to ask the question here. Suppose I want to implement a method operate, which computes the matrix-vector product. I read a long time ago that it was better to have a method signature like void operate(double[] x, double[] y) where x is the vector to be multiplied, and y the result. Such a choice avoids costly (so they said) memory allocations caused by a signature like double[] operate(double[] x) The thing is the first option is not frequently met in Commons-Math. I've started to work with this option for iterative linear solvers, but I do not like the inconsistent feel it has with the rest of CM. Also, very crude monitoring on rather large linear systems (800,000 x 800,000) shows that memory allocations are not even measurable... As I said, I read that a long time ago, and someone already mentioned on this forum that GC is getting pretty good those days... So is it really worth worrying about memory allocation? I do not intend to do a thorough benchmarking, but I'd rather like to get rid of operate(double[], double[]) and keep only the most natural one. Any thoughts on this ? Sebastien --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
