http://www.phy.mtu.edu/~suits/notefreqs.html
Remember, there are 13 keys in each "octave". The sharps and flats allow you to play in any key without re-tuning.
That table should do it! Although I don't think you can use float values in tone(), so if you care about having it properly in-tune, you may need another approach. If not, just bang in the closest value rounded up or down to suit, and hope for the best.