from bumps.names import *

scale = 10
sigma = 0.1 * scale
# sigma = 0.001*scale  # Too small
# sigma = 10*scale   # Too large

def fn(a, b):
    return 0.5 * min(abs(a + b), abs(a - b)) ** 2 / sigma**2 + 1


M = PDF(fn, a=3 * scale, b=1.2 * scale)

M.a.range(-3 * scale, 3 * scale)
M.b.range(-1 * scale, 3 * scale)

problem = FitProblem(M)