Moving Average Convergence / Divergence

#include<iostream>
#include<array>
#include<fstream>
#include<vector>
#include<iomanip>

template<class T>
void mult(T&);
double macd(const std::array<double, 26>&, const std::vector<double>&, const std::array<double, 12>&, int);
double signal(const std::array<double, 974>&, const std::array<double, 9>&, int);

int main()
{
    std::vector<double> data;
    data.reserve(1000);

    std::fstream file;

    file.open("dane.txt", std::ios::in);
    double tmp;
    while (file >> tmp)
        data.emplace_back(tmp);
    file.close();

    std::array<double, 26> backward26;
    std::array<double, 12> backward12;
    std::array<double, 9> backward9;
    std::array<double, 965> signalArray;
    std::array<double, 974> macdArray;

    mult(backward26); mult(backward12); mult(backward9);

    for (int i = 0; i < macdArray.max_size(); i++)
        macdArray[i] = macd(backward26, data, backward12, i+27);

    for (int i = 0; i < signalArray.max_size(); i++)
        signalArray[i] = signal(macdArray, backward9, i + 10);

    std::fstream macdFile, signalFile;
    macdFile.open("macd.txt", std::ios::out);
    signalFile.open("signal.txt", std::ios::out);

    for (int i = 0; i < signalArray.max_size(); i++) {
        macdFile << std::fixed << std::setprecision(5) << macdArray[i + 9] << std::endl;
        signalFile << std::fixed << std::setprecision(5) << signalArray[i] << std::endl;
    }


    macdFile.close();
    signalFile.close();

    return 0;
}

template<class T>
void mult(T& array) {
    double alfa = 1.0 - (2.0 / (array.max_size() - 1));
    array.fill(alfa);
    for (int i = 1; i < array.max_size(); i++)
        array.at(i) = array.at(i - 1) * array.front();
}

double macd(const std::array<double,26>& backward26, const std::vector<double>& data, const std::array<double,12>& backward12, int place) {
    place -= 2;
    double ema12 = data[place + 1], ema26 = data[place + 1];

    double tmp = 1;
    for (int i = 0; i < 26; i++)
        ema26 += (data[place - i] * backward26[i]);
    for (int i = 0; i < 26; i++)
        tmp += backward26[i];
    ema26 /= tmp;

    tmp = 1;
    for (int i = 0; i < 12; i++)
        ema12 += (data[place - i] * backward12[i]);
    for (int i = 0; i < 12; i++)
        tmp += backward12[i];
    ema12 /= tmp;

    return (ema12 - ema26);
}

double signal(const std::array<double, 974>& macdArray, const std::array<double, 9>& backward9, int place) {
    place -= 2;
    double sig = macdArray[place + 1];

    double tmp = 1;
    for (int i = 0; i < 9; i++)
        sig += (macdArray[place - i] * backward9[i]);
    for (int i = 0; i < 9; i++)
        tmp += backward9[i];
    sig /= tmp;
    return sig;
}