Includes delta and gamma calculations

central difference delta and non uniform grid gamma
buy sell positions different strategy
positions

1) problem with global name in line 81
2) incorporate the differentials for the delta and the gamma
3) add noise part, and calculate s(i+1) and v(i+1).
updated positions file

debugged the file and it works but not able to identify positions
positions_latest

with the actual delta and gamma eqns for counter 3.