[Rcpp-devel] Overflow error when creating a large matrix

[Alessandro Mammana]

Dear All,
When creating a large matrix with the follwing code:

#include <Rcpp.h>
// [[Rcpp::export]]
Rcpp::IntegerMatrix makeMat(int nrow, int ncol){
        Rcpp::IntegerMatrix mat(nrow, ncol);
        return mat;
}

I get the error:

Error in .Primitive(".Call")(<pointer: 0x7f86936d3ea0>, nrow, ncol) :
  negative length vectors are not allowed

Where nrow*ncol is a very large number (about 3*10^9). I understand
that such a number cannot be represented by an int type, but this does
not seem to be a problem when in R I do:

> mat <- matrix(0, nrow=nrow, ncol=ncol)

Questions:
1. why is the behaviour different between R and Rcpp in the allocation
of a matrix?
2. In a 64 bits machine, what is actually the maximum allowed length
of a vector/matrix? does the length of a vector/matrix need to be
represented by an int?

Thanks a lot and best regards,
Alessandro

-- 
Alessandro Mammana, PhD Student
Max Planck Institute for Molecular Genetics
Ihnestraße 63-73
D-14195 Berlin, Germany