Hello, everyone. I guess the probrem maybe occur because of sourceCpp(), so I have made another test. I make a simple package using RcppArmadillo.package.skeletion(). But the same problem appear. My code is on Github: https://github.com/ZhangYet/RcppTest Is there anything related to my compiler or OS? I use 64-bit CentOS and g++ 4.4.5
On Sat, Jan 18, 2014 at 2:01 AM, 张晔 <zhang...@gmail.com> wrote: > Thanks, Dirk. > I have upload my code to Github: https://github.com/ZhangYet/RcppTest/ > And I made a mistake: > > > | res1 <- mydcov(x,y)/sqrt(mydcov(x,x)*mydcov(y,y)) > | > | a <- mydcov(x,y) > | b <- mydcov(x,x) > | c <- mydcov(y,y) > | res2 <- a/sqrt(b*c) > | > | and res2 is different from res1.(res2 is the right answer.) > > I checked my test result. res2 is not the right answer, but it's different > from res. > > 于 2014/1/17 21:36, Dirk Eddelbuettel 写道: > > On 17 January 2014 at 20:51, 晔张 wrote: >> | Dear all, >> | >> | I have a strange question such that I can't conclude it in the title. >> | I have write an function: >> | //[[Rcpp::export]] >> | double mydcov(NumericVector x, NumericVector y) >> >> It would help us to see the function to have any guess at what may be >> wrong. >> | This function is computing ditance covariance. This function is OK. >> It give >> | the right answer. >> | I use this function to compute distance correltion. >> | >> | //[[Rcpp::export]] >> | double mydcor(NumericVector x, NumericVector y) >> | { >> | return mydcov(x,y)/sqrt(mydcov(x,x)*mydcov(y,y)); >> | } >> | >> | Then, I compile the source code using sourceCpp. >> | And then mydcor(x,y) give a wrong answer. >> | >> | Here comes the strange part: >> | In R, I run code as follow >> | >> | res1 <- mydcov(x,y)/sqrt(mydcov(x,x)*mydcov(y,y)) >> | >> | a <- mydcov(x,y) >> | b <- mydcov(x,x) >> | c <- mydcov(y,y) >> | res2 <- a/sqrt(b*c) >> | >> | and res2 is different from res1.(res2 is the right answer.) >> | >> | And I have another test, rewriting the source code for mydcor(): >> | version1: >> | //[[Rcpp::export]] >> | double mydcor(NumericVector x, NumericVector y) >> | { >> | double a = mydcov(x,y) >> | double b = mydcov(x,x); >> | double c = mydcov(y,y); >> | return (a/sqrt(b*c)); >> | } >> | >> | version2: >> | //[[Rcpp::export]] >> | double mydcor(NumericVector x, NumericVector y) >> | { >> | double a = mydcov(x,y) >> | Rcout<<a<<"\n"; >> | double b = mydcov(x,x); >> | Rcout<<b<<"\n"; >> | double c = mydcov(y,y); >> | Rcout<<c<<"\n" >> | return (a/sqrt(b*c)); >> | } >> | This time, version2 make a right answer. >> | It's too weird. I havn't meet such situation before. >> >> I am not sure we are in a position to help you here. >> >> Regards, Dirk >> >> | >> | Happy Lunar New Year (the most important festival in China), and Thanks >> in >> | advance. >> | >> | Best regards >> | ZhangYet >> | >> | ---------------------------------------------------------------------- >> | _______________________________________________ >> | Rcpp-devel mailing list >> | Rcpp-devel@lists.r-forge.r-project.org >> | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel >> > >
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