Storing calculated values

I'm having trouble finding a method of storing basic numerical values.

My programme works out projectile velocity, acceleration and coordinates at certain times and I need it to store these values at the times.

So basically I need to store,

(t, x, y, z)
(t, x', y', z')
(t, x'', y'', z'')

at user specified times (for example if the user enters 0.2 at times 0, 0.2, 0.4, 0.6 until the programme ends)

Also, is there a way to limit the amount of decimal places a value goes to if it is stored as single?

[QUOTE=Raidea] need it to store these values at the times.

Try