save serial data to variable?

yeah I know n and m should be moved. they'll be put at the beginning of loop().

And yes, the values that are printed each have 4 decimal places. So thanks for confirming about the atof.

To null terminate the 2 new arrays do I have to do anything? or will it be fine since I made the arrays 1 larger than they need to be so the last spot should be a null right?