Update de_snooker.py

[yhwang17]

Fix Unit Vector Calculation and Adjust Metropolis Calculation in get_proposal

• The vector delta was normalized using u = delta / np.sqrt(norm(delta)).

  • This approach is mathematically incorrect because dividing by sqrt(norm(delta)) does not produce a unit vector (a vector with magnitude 1).
  • As a result, the vector u had an incorrect magnitude, which could lead to:
    • Misaligned scaling in the generated proposals (q).
    • Errors in the Metropolis acceptance ratio due to incorrect distance calculations.

• Fix:

  • The calculation has been corrected to divide delta by norm(delta), ensuring it is a unit vector as intended.
  • The Metropolis acceptance criterion scaling factor was adjusted from 0.5 * (ndim - 1.0) to ndim - 1.0 accordingly.