There is an example of Newton-Raphson here: https://code.jsoftware.com/wiki/NYCJUG/2010-11-09#Newton.27s_method .
On Sat, Dec 25, 2021 at 2:17 PM Henry Rich <[email protected]> wrote: > What I meant was, if you are tempted to add verbs for various domains, > datatypes, definitions of integration, etc, you don't have a complete > spec. That's where I think we are with d./D. . You will end up with > two entry points defined as primitives, and who knows how many as named > verbs. The correct number of primitives for an application like that is 0. > > Henry Rich > > On 12/25/2021 2:08 PM, Raul Miller wrote: > > On Sat, Dec 25, 2021 at 11:11 AM Henry Rich <[email protected]> > wrote: > >> It is possible to have d. and D. call an addon, but I don't see that > >> that makes it much better. And, primitives should only be functions > >> that have a cast-iron spec. > > I believe that d. and D. do have a cast iron spec. The problem we face > > with them is the implementation of that spec is daunting. > > > > Past practice here has been to throw nonce errors for parts of the > > infinite domain which are currently not treatable and to construct > > verbs who return the primary value when that's an issue and a domain > > error for values where the original function was known to be not > > differentiable. > > > > That said, J's documentation should document the limitations of > > floating point numbers at least briefly, and should similarly document > > the limitations of analytic mechanisms like d. and D. at least > > briefly. > > > > (And, in this context, it's worth noting that the "cast iron spec" for > > floating point numbers has resulted in the industry supporting quite a > > variety of floating point numbers -- J supports a subset of those > > formats, with one which fits the host machine's architecture as the > > primary format. This is relevant here because the limitations on > > floating point numbers are intimately tied to limitations of > > approaches for the d. family of operations.) > > > > (Also, I think that the d. documentation should have an implementation > > of the Newton Raphson algorithm as an example.) > > > > Thanks, > > > > > -- > This email has been checked for viruses by AVG. > https://www.avg.com > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA Quantitative Consultant ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
