# Need more float precision

I have a Physics problem which huge and tiny numbers and Mathematica just gives me a speed of my particles which is the speed of light. Then $1/\sqrt{1-v^2/c^2}$ becomes singular.

If I use smaller values for my radius r, it works, but with the radius of 300 light years, I just get error messages.

Is there some way to increase the precision or something like that?

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Have you tried using e.g. q = SetPrecision[q, 50] on all numeric variables? You could also try Rationalize. Be aware that either of these will be generating false precision. – Mr.Wizard Jun 16 '12 at 20:26
I tried SetPrecision[number, Infinity] and it works now. I am aware that the precision of my answer is not correct, but I just need it for a Physics homework example. – Martin Ueding Jun 16 '12 at 20:32
okay, I'll post that as an answer. – Mr.Wizard Jun 16 '12 at 20:34
Did you consider using Hartree Units? en.wikipedia.org/wiki/Natural_units#Summary_table – Dr. belisarius Jun 16 '12 at 20:40
@belisarius: Interesting! I usually only use SI since I avoid any conversion then. I'll put that in the back of my mind though. – Martin Ueding Jun 16 '12 at 20:43

You can use SetPrecision to set the interpreted precision of a numeric value, or Rationalize to convert it into an exact value.