Appart from the implementation of atoF() (great!) not sure if additional things need to be fixed:

Regarding:

```
  number1 = wsStrip(number1);
  number2 = wsStrip(number2);
```

What does this wsStrip() function? Removing initial/final whitespace (which is ok) or also in the middle (which would not be ok, as it "hides" number format fails for atoF())?