vector<double> v1, v2, v3;
ofstream ofs("daten.txt");
ofs.precision(10);
//annahme: alle vektoren haben gleich viel daten
for(size_t i = 0; i < v1.size(); ++i)
{
  ofs << v1[i] << ' ' << v2[i] << ' ' << v3[i] << endl;
}

und using namespace std; sollte noch irgendwo hin

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <ctime>

using std::vector;
using std::ofstream;
using std::endl;

int main()
{
	srand(time(0));
	vector<double> v1, v2, v3, v4;

	std::generate_n(std::back_inserter(v1), rand()%100, rand);
	std::generate_n(std::back_inserter(v2), rand()%100, rand);
	std::generate_n(std::back_inserter(v3), rand()%100, rand);
	std::generate_n(std::back_inserter(v4), rand()%100, rand);

	ofstream out("YOURFILE.TXT");

	std::ostream & of = (true) ? std::cout : out;

	std::size_t index = 0;
	while ( index < v1.size() || index < v2.size() || index < v3.size() || index < v4.size() ) // unschön :(
	{
		of.width(15);
		of.precision(10);

		of << std::fixed << std::right << std::showpos;

		if ( index < v1.size() )
			of << v1[index] << " ";
		if ( index < v2.size() )
			of << v2[index] << " ";
		if ( index < v3.size() )
			of << v3[index] << " ";
		if ( index < v4.size() )
			of << v4[index];

		of << endl;
	}

	return 0;
}