source: util/stochastik.cpp@ cfaf42

using namespace std;
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
#include <math.h>
#include <string>


int main(int argc, char **argv) {

        double avg, dev;
        double tmp;
        int i, j, col, zaehler;
        int ecut;
        int flag;
        FILE *test;
        string zeile;
        
        if (argc < 4) {
                cout << "Usage: " << argv[0] << " <Spalte> <X> <File1> <File2> ...\n";
                return(1);
        } 
        col = atoi(argv[1]);
        ecut = atoi(argv[2]);

        // get average
        avg = 0.;
        zaehler=0;
        for (i=3;i<argc;i++) {
                //cout << "Reading column " << col << " from file " << argv[i] << "\n";
                ifstream test(argv[i]);
                if (test == NULL) { cout << "Can't open File " << argv[i] << "\n"; return(255); }
                flag=1;
                //cout << "Looking for " << ecut << " \n";
                while (getline(test, zeile, '\n')) {
                        //cout << zeile;
                        istringstream input(zeile);
                        input >> ws >> tmp;                     
                        if (tmp==(double)ecut) {        // found correct line!
                                for (j=col;j>0;j--)
                                        if (!input.eof())
                                                input >> ws >> tmp;
                                        else
                                                flag=0;
                                //cout << tmp << "\n";
                                avg += tmp;
                        } 
                        //else cout << " skipping\n";
                }
                zaehler+=flag;
                test.close();
        }
        if (zaehler != 0) avg /= zaehler;       

        // get deviation
        dev = 0.;
        zaehler=0;
        for (i=3;i<argc;i++) {
                //cout << "Reading column " << col << " from file " << argv[i] << "\n";
                ifstream test(argv[i]);
                if (test == NULL) { cout << "Can't open File " << argv[i] << "\n"; return(255); }
                flag=1;
                while (getline(test, zeile, '\n')) {
                        istringstream input(zeile);
                        input >> ws >> tmp;                     
                        if (tmp==(double)ecut) {        // found correct line!
                                for (j=col;j>0;j--)
                                        if (!input.eof())
                                                input >> ws >> tmp;
                                        else
                                                flag=0;
                                //cout << tmp << "\n";
                                dev += pow(tmp - avg, 2);
                        }
                }
                zaehler+=flag;
                test.close();
        }
        //dev = 1/(zaehler)*dev;
        dev /= zaehler;
                        
        cout << setprecision(8) << avg << "\t" << setprecision(8) << sqrt(dev) << "\n";
        return(0);
}