Help me write Fortran code

[jimmytung]

I'm looking for a fortran code to calculate second-order derivative from a dataset. Please help me!

[minger]

Write a subroutine which calculates a derivative based on any method you want. Send your data to that subroutine to calculate the first derivative, then re-send that data again to get the second derivative.

[jimmytung]

thank you very much!