template <typename Derived>
void PrintMatrix(const EigenBase<Derived>& M, int row_th, int nRows)
//void PrintMatrix(MatrixXd & M, int row_th, int nRows)
{
cout<<left<<setw(8)<<setfill(' ')<<" ";
for (int j=0;j<M.cols();j++)
{
cout<<"\t"<<setw(8)<<(j);
}
cout<<endl;

for (int i=0;i<nRows;i++)
{
cout<<left<<setw(8)<<setfill(' ')<<row_th+i;
for (int j=0;j<M.cols();j++)
{
cout<<"\t"<<setw(8)<<M(i+row_th,j);
}
cout<<endl;

}

}
-----------------------------
Above is my function for print Eigen Matrix in a customized way. It used to work if the matrix argument is MatrixXd. Now I want to make the argument can be any matrix type. I read documentation and thought this is easy. But an error cannot be avoid as:

"Undefined symbols for architecture x86_64:
"void PrintMatrix<Eigen::Matrix<double, -1, -1, 0, -1, -1> >(Eigen::EigenBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> > const&, int, int)", referenced from:
S5_Sort1NNByCommonFace_BCC() in S5_Sort1NNByCommonFace_BCC-2cc757.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)"

I guess maybe some other things are wrong?

Thanks,

L

This is probably because you defined your function in a separate cpp file. Template functions must be defined in header files.

Thank you! I fixed it. You are always very helpful.

L