On 12 December 2014 at 10:09, Devin wrote:
| ... but you can't set a mathematical operation equal to a string. I also
tried:
|
| int test()
| {
| gsl_set_error_handler_off();
| if(gsl_sf_hyperg_2F1(1,1,1.1467003,1) == NAN){
| std::cout << "Error" << std::endl;
| }
| return 0;
| }
|
| ... but the if-branch gets ignored. How can I achieve that the program runs
through the if-branch?
Use a proper test for NaN.
See eg http://gallery.rcpp.org/articles/working-with-missing-values/ or other
documentation as eg the Writing R Extensions manual, my Rcpp book -- or the
content of the Rcpp package.
A simple way, using a macro from the R headers, is
R> cppFunction('bool isItNan(double foo) { return ISNAN(foo); }')
R> isItNan(NaN)
[1] TRUE
R> isItNan(3.14)
[1] FALSE
R> isItNan(3L)
[1] FALSE
R>
There are (better) alternatives in the Rcpp sources, but some of the
behaviour is subtle. Kevin once wrote a great answer at StackOverflow:
http://stackoverflow.com/questions/26241085/rcpp-function-check-if-missing-value/26262984#26262984
Dirk
--
http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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