def himmelblau(p):
    x, y = p
    a = x*x + y - 11
    b = x + y*y - 7
    return a*a + b*b
R^2 -> R^1 test function for optimization.  The function has four local
dataset/ETHPy150Open scipy/scipy/scipy/optimize/tests/test_optimize.py/himmelblau