QtConcurrent question

[bair]

I am writing a program which performs some heavy calculations, so I'm exploring QtConcurrent. I've looked at the QtConcurrent Progress Dialog Example and tried to use QtConcurrent::map() in the same way. Here is my code:

void MainWindow::some_member_function()
{
    ...
    QVector<int> vector;
    int iterations=int(Ntotal/1000000)+1;
    for (int i = 0; i < iterations; ++i)
        vector.append(i);
    ...
    futureWatcher.setFuture(QtConcurrent::map(vector, cycle)); // <----- error
    ...
}
void MainWindow::cycle(int &start)
{
    //lots of calculations
...
}

void MainWindow::some_member_function()
{
    ...
    QVector<int> vector;
    int iterations=int(Ntotal/1000000)+1;
    for (int i = 0; i < iterations; ++i)
        vector.append(i);
    ...
    futureWatcher.setFuture(QtConcurrent::map(vector, cycle)); // <----- error
    ...
}
void MainWindow::cycle(int &start)
{
    //lots of calculations
...
}

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I'm getting this error:

mainwindow.cpp:345: error: argument of type `void (MainWindow::)(int&)' does not match `void (MainWindow::*)(int&)'

I'm confused. How should I use my member function cycle() in QtConcurrent::map() properly?