Dear R developers,
I noticed that core R distribution functions return NaN, when parameter
values are out of parameter space. I have looked in source code and
found that warnings and return of NaN are done internally in C code. For
dgamma.c the line 49 is:
if (shape <= 0 || scale <= 0) ML_ERR_return_NAN;
OK. How should this be implemented if distribution functions are written
directly in R? I came up with this
if (any(shape <= 0)) {
warning("shape must be positive")
return(NaN)
}
I think that it would be nice that returning NaN for undefined parameter
values in distribution functions would also be documented in Writing R
Extension.
--
Lep pozdrav / With regards,
Gregor Gorjanc
----------------------------------------------------------------------
University of Ljubljana PhD student
Biotechnical Faculty
Zootechnical Department URI: http://www.bfro.uni-lj.si/MR/ggorjan
Groblje 3 mail: gregor.gorjanc <at> bfro.uni-lj.si
SI-1230 Domzale tel: +386 (0)1 72 17 861
Slovenia, Europe fax: +386 (0)1 72 17 888
----------------------------------------------------------------------
"One must learn by doing the thing; for though you think you know it,
you have no certainty until you try." Sophocles ~ 450 B.C.
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