Q:

Android SeekBar Math

I have a seekbar, and would like to take the progress (0 - 100) and convert it to -100 to +100. I am not too good at coming up with formulas like this, so I was hoping I could get some thoughts on a formula to do this.
If setting default min and max values are possible I don't want to do that because the seekbar min and max values could change so doing math is better idea IMO.
Thanks for the help!

A:

You need to rescale from a width of 100 to 200 first, then set your basis to -100. So your function would be something like f(x) = x*2 - 100

