> On 10 Jan 2020, at 18:12, Gilles Sadowski <gillese...@gmail.com> wrote: > >> ... > > IIUC, precision (without resorting to "BigDecimal") was the purpose of > "LinearCombination". +1 for making the appropriate changes to the > existing "value" method. > [I'd suggest to open a JIRA issue and mention the rest of the alternatives > there, for future reference; but I wouldn't add them to the API until there > is a need for it.]
OK. If the purpose is precision and to avoid BigDecimal then switching to dot3 seems the best option as it performs one pass over the round-off errors to improve the summation in the case of badly conditioned dot products. This is an alternative to sorting the input products before (and during) summing and faster. I’ll write the code to allow expansion to dot4, dot5, etc but not add this to the API. Previously I used the timings from the summation only for the 2.2x slower estimate. The timings for the dot product are better. Dot2 to dot3 should be 12.5 to 18.5 so about 50% slower (table 6.5 in Ogita’s paper). I am going to set up a JMH module for numbers as I would like to benchmark the operations in Complex. This is for reference with regard to the idea to create the previously discussed ComplexList that stores the numbers as primitive arrays and then does operations by creating instances of Complex and then returning the results to the primitive arrays. I hope to show that for most operations the overhead of creating Complex objects is negligible. There may be cases where special implementations would be useful such as multiply or divide of two lists in a paired operation. I was going to use the format from [rng] for the JMH module thus: commons-numbers/commons-numbers-examples/examples-jmh However I do not have any other examples. So perhaps just a single child module that is included via a profile as it need not be a distributed artifact: commons-numbers/commons-numbers-mmh WDYT? I can build the new LinearCombination methods and put the old ones in the jmh project with a test of relative speed. Then I’ll get back to Complex (which is nearing completion) and the ComplexList. Alex
