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From |
Francesca Colantuoni <f.colantuoni9@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: macro `if' in nonlinear least squares |

Date |
Thu, 2 May 2013 11:48:14 -0400 |

Thanks Nick for your response. I did not find this explanation in [U]nl, but I have not tried -help nl-. If I understand correctly, unless I have other rescrictions for subsamples, the `if' will not matter, but it's part of the routine. Francesca On Thu, May 2, 2013 at 11:33 AM, Nick Cox <njcoxstata@gmail.com> wrote: > See the help and manual entry for -nl-. The short answer is that for > generality a program must have a way of working with subsets. If you > are all the data, `if' is empty and no restriction is applied. > > "Function evaluator programs must accept a varlist, an if exp, and an > option named at() > that accepts the name of a matrix. It may optionally accept > weights as well. Unlike > substitutable expression programs, a function evaluator program is > not declared to be > r-class. The outline of a nlfunc_prog program is > > program nlfunc_prog > version 10 > syntax varlist [aw fw iw] if, at(name) > local lhs: word 1 of `varlist' > local rhs: subinstr local varlist "`lhs'" "", word > (evaluate the function at at matrix) > replace `lhs' = <the function values> `if' > end > > When evaluating your function, remember to restrict the estimation > sample by using `if'." > Nick > njcoxstata@gmail.com > > > On 2 May 2013 16:27, Francesca Colantuoni <f.colantuoni9@gmail.com> wrote: >> I am programming a nonlinear least square regression, and I am trying >> to find the best way to do it based on variuos examples that I found >> online. >> >> In the following code, I have trouble understanding what stata does >> with the macro `if' at the end of the generate command. Would anybody >> clarify that for me? I could not find an explanation for this use of >> "if" in either [P] or [U] manual (or Google). >> >> // Some temporary variables >> tempvar kterm lterm >> generate double `kterm' = `delta'*`capital'^(-1*`rho') `if' >> generate double `lterm' = (1-`delta')*`labor'^(-1*`rho') `if' >> >> // Now fill in dependent variable >> replace `logout' = `b0' - 1/`rho'*ln(`kterm'+`lterm') `if' >> >> Best Regards, >> Francesca >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: macro `if' in nonlinear least squares***From:*Francesca Colantuoni <f.colantuoni9@gmail.com>

**References**:**st: macro `if' in nonlinear least squares***From:*Francesca Colantuoni <f.colantuoni9@gmail.com>

**Re: st: macro `if' in nonlinear least squares***From:*Nick Cox <njcoxstata@gmail.com>

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