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...olve the StRD nls test problems. ... Excel solver does have the virtue that it will always produce an answer, albeit one with zero accurate digits." --- I also leave it to others to modify what is excerpted if appropriate. Cheers, Bert On Wed, Feb 20, 2013 at 7:58 AM, Bruce McCullough <bdmccullough at drexel.edu> wrote: > The idea that the Excel solver "has a good reputation for being fast and > accurate" does not withstand an examination of the Excel solver's > ability to solve the StRD nls test problems. Solver's ability is > abysmal. 13 of 27 "answe...

...in R? Please reply to me. I will post a summary to the list. Bruce PS: I believe that in R I should delete the "log" and instead use the "log.p=T" option; presumably it is numerically more efficient. If this is incorrect, please let me know. B. D. McCullough bdmccullough at drexel.edu www.pages.drexel.edu/~bdm25 w: 215-895-2134 f: 215-895-2907 Associate Professor Department of Decision Sciences Academic Building room 230 Drexel University Philadelphia, PA 19104 ``...

The idea that the Excel solver "has a good reputation for being fast and accurate" does not withstand an examination of the Excel solver's ability to solve the StRD nls test problems. Solver's ability is abysmal. 13 of 27 "answers" have zero accurate digits, and three more have fewer than two accurate digits -- and this is after tuning the solver to get a good