I am trying to sort vectors by using: 

```
sort(vec1.begin(), vec1.end(),rankComboEnergy);

```

However, I have an additional term (FE\_scale) in the boolean expression, which I'd like to vary, depending on the command-line arguments.

```
bool rankComboEnergy(Coordinates2 first, Coordinates2 second) {
    return (first.Energy + FE_scale*first.FEnergy < second.Energy + FE_scale*second.FEnergy);
}

```

I tried a few different things, but am not having much luck.