C ++中用于增强矩阵的模板化函数

Question

I require a function to print out the elements of a vector in a format that I'd like to see. As of now, I have separate functions for vector<double> and vector<std::complex> , as follows:

void printvd(boost::ublas::vector<double> V) {
    for( int i=0;i<V.size();i++ )
      std::cout << V(i) << " ";
}
void printvc(boost::ublas::vector<std::complex> V) {
    for( int i=0;i<V.size();i++ )
      std::cout << V(i) << " ";
}

I've tried templating with,

template<typename T>
void printv(boost::ublas::vector<T > V) {
    for( int i=0;i<V.size();i++ )
      std::cout << V(i) << " ";
}

but any calls (like printv<double>(V); ) invariably ends up with an undefined reference error.

I am facing similar issues with matrices too - any help would be appreciated. It would also be good if somebody could quip in about how to make use of matrix expressions in boost.

Answer 1

Please make sure you can compile this very basic example, where all paths&includes should be resolved.

#include <iostream>
#include <boost/numeric/ublas/vector.hpp>
#include <complex>

using std::cout;
using std::endl;

void printvd(boost::numeric::ublas::vector<double> V) {
    for( int i=0;i<V.size();i++ )
      std::cout << V(i) << " ";
}
void printvc(boost::numeric::ublas::vector<std::complex<double>> V) {
    for( int i=0;i<V.size();i++ )
      std::cout << V(i) << " ";
}

template<typename T>
void printv(boost::numeric::ublas::vector<T > V) {
  for( int i=0;i<V.size();i++ )
      std::cout << V(i) << " ";
}

int main(int argc, char *argv[])
{
  boost::numeric::ublas::vector<double> testVector1;
  boost::numeric::ublas::vector<std::complex<double>> testVector2;

  printv(testVector1);
  printv(testVector2);
  return 0;
}

And corresponding CMakeLists.txt:

project(boost_vector_test)
cmake_minimum_required(VERSION 2.8)
add_executable(${PROJECT_NAME} main.cpp)

Otherwise boost has good documentation with examples how to use matrix expressions: http://www.boost.org/doc/libs/1_63_0/libs/numeric/ublas/doc/matrix_expression.html