asymmetry functions

This module defines the following functions:

• get_4counter(Fp, Fn, Bp, Bn): Four-counter asymmetry
• get_4counter_err(Fp, Fn, Bp, Bn): Four-counter asymmetry error
• get_4counter_err_bkgd(Fp, Fn, Bp, Bn, n_prebeam): Four-counter asymmetry error, accounting for background subtraction
• get_simple(F, B): Simple asymmetry (F-B)/(F+B)
• get_simple_err(F, B): : Simple asymmetry error
• get_simple_err_bkgd(F, B, n_prebeam): Simple asymmetry error, accounting for background subtraction
• get_alpha(a, b): alpha diffusion
• get_alpha_err(a, b): alpha diffusion error
• get_alpha_err_bkgd(a, b, n_prebeam): alpha diffusion error, accounting for background subtraction