--- On Tue, 6/9/09, Skipper Seabold <[email protected]> wrote: > I have implemented the ipmt and ppmt functions that were > "not > implemented" in numpy.lib.financial as well as written some > tests.
Thanks! > ipmt is one of the functions where there was a discrepancy > between > what OO and Excel report for the beginning of period > payment > assumptions and what Gnumeric and Kspread report as stated > in the > OpenFormula document referenced above (I discovered errors > in this > document as well as the openoffice documents referenced btw > but they > become obvious when you work these problems out). And the nightmare worsens (IMO). > OpenFormula lists > the Gnumeric/Kspread as the "result" in the document, but > there is > still a question to which is correct. Well, I was > able to derive both > results, and as I suspected the Gnumeric/Kspread was based > on an > incorrect assumption (or a mistake in implementation) not a > different > formula. My point with the derivations wasn't to > include them in the > documentation, but rather to find out what assumptions are > being made > and then deduce which results are correct. In the > cases of these > simple spreadsheet functions I think it should be obvious > if it's > right or wrong. OK, I concede defeat: if it is the wisdom of the PTB that numpy.financial be retained, I will stop messing w/ their help doc, 'cause I'm clearly in over my head. DG > If there is any interest in adding the ipmt and ppmt > functions now, I > can apply a patch. If not, I can keep them separate > as I work on the > other functions. > > Cheers, > > Skipper > _______________________________________________ > Numpy-discussion mailing list > [email protected] > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ Numpy-discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
