mizoGrad 0.1.0

Very Fast Gradient-Based Optimization Algorithm

mizoGrad: Search & Accelerate Gradient-Based Algorithm

Description

This module is dedicated to the implementation of the Gradient-based box constrained optimization proposed in this paper.

This algorithm combines the following features:

• Line search along the gradient line
• Line search along the acceleration path
• Provable asymptotic convergence to a solution meeting the KKT-optimality conditions.

The abobe mentioned paper shows that the algorithm outperfoms almost all existing gradient-based methods on a set of benchmark problems proposed in the kaggle repository.

Installation

pip install mizoGrad

Input arguments

The user needs to provide the following mandatory input arguments:

• The first, say cost, represents the cost functiont to be minimized
• The second, say cost_gradient, is the gradient of the same cost funciton
• The number of decision variable nx

Note: The names cost and cost_gradient are example, only their key fields are detremined which are f and g resptively (see the example below).

The complete list of input parameters (including all those with defaults values) is given on the following table:

Parameter	Type	Default	Description
f	callable	—	Cost function to minimize
g	callable	—	Gradient of the cost function
nx	int	—	Number of decision variables
xmin	ndarray	[-inf] * nx	Lower bound on the decision variable
xmax	ndarray	[+inf] * nx	Upper bound on the decision variable
ng	int	5	Number of exploration points
alpha_min	float	-8	lower initial exponent on the step
alpha_max	float	0	Higher initial exponent on the step
ng	int	5	Number of exploration points
fast_min	float	-0.2	Maximum number of iterations
fast_max	float	1	Maximum number of iterations
rho_adapt	float	0.05	Adaptation ratio
eta	float	10^{-16}	Small step (<1/L)

Returned solution

The returned solution is a dictionary with the following format:

Dictionary key	Type of value	Description
xopt	ndarray	The best solution found
fopt	float	The corresponding best cost function value
normG	float	The norm of the gradient at solution
lesalpha_min	ndarray	The sequence of values taken by alpha_min
lesalpha_max	ndarray	The sequence of values taken by alpha_max
traj	ndarray	The sequence of values of the cost
traj_c	ndarray	The sequence of step sizes on the acceleration direction

Example of use

import numpy as np
from mizoGrad import GradOptimizer
from time import time

#from SaA import GradOptimizer

np.set_printoptions(formatter={'float': lambda x: "{0:0.4f}".format(x)})

# Define the cost function and the gradient

def cost(x, a=10, b=2, m=1):

    f = np.power((x[0]-a)*x[1] + b * x[2] ** 3, 2*m)
    return f

def cost_gradient(x, a=10, b=2, m=1):
    term = 4 * np.power((x[0]-a)*x[1] + b * x[2] ** 3, 2*m-1)
    g = np.array([
        term * x[1],
        term * (x[0]-a),
        term * (3 * b * x[2] ** 2)
    ])
    return g


x0 = 2*np.array([1,1,1])

xmin = np.array([-5] * len(x0))
xmax = np.array([+5] * len(x0))

s2a = GradOptimizer(
    f=cost,
    g=cost_gradient,
    nx = 3,
    xmin=xmin,
    xmax=xmax,
    ng=5,
    alpha_min=-8,
    alpha_max=0,
    fast_min=-0.2,
    fast_max=1.0,
    rho_adapt=0.05,
    eta=1e-16,
)

# set the dictionary argument used the cost function and gradient 

kwargs = dict(
    a=3,
    b=1,
    m=1,
)

# solve the problem

t1 = time()
R = s2a.solve(x0=x0, kwargs=kwargs, maxIter=20, epsG=1e-8, display=True)
cpu = time()-t1

print('solution: ', np.array(R['xopt'], dtype=float))
print('best cost : ', cost(s2a.y, **kwargs))
print('cpu = ', cpu)

which gives the following results:

value 9.374756801 normg=292.957 | alpha_min=-8.0 | alpha_max=-0.4
value 3.931283917 normg=31.930 | alpha_min=-8.0 | alpha_max=-0.78
value 1.109572100 normg=17.759 | alpha_min=-7.962 | alpha_max=-0.419
value 0.000013588 normg=6.499 | alpha_min=-7.922 | alpha_max=-0.04185
value 0.000000666 normg=0.066 | alpha_min=-7.922 | alpha_max=-0.4359
value 0.000000029 normg=0.015 | alpha_min=-7.922 | alpha_max=-0.8102
value 0.000000000 normg=0.003 | alpha_min=-7.922 | alpha_max=-1.166
value 0.000000000 normg=0.000 | alpha_min=-7.922 | alpha_max=-1.504
value 0.000000000 normg=0.000 | alpha_min=-7.922 | alpha_max=-1.825
value 0.000000000 normg=0.000 | alpha_min=-7.89 | alpha_max=-1.52
value 0.000000000 normg=0.000 | alpha_min=-7.89 | alpha_max=-1.838
value 0.000000000 normg=0.000 | alpha_min=-7.859 | alpha_max=-1.536
value 0.000000000 normg=0.000 | alpha_min=-7.859 | alpha_max=-1.852
solution:  [1.7020 -1.2326 -1.1696]
best cost :  8.860672896017431e-21
cpu =  0.0008881092071533203

Citing mizoGrad

@misc{alamir2026nonlinearmodelpredictivecontrol,
      title={A Nonlinear Model Predictive Control Perspective on Gradient-Based Optimization: A New Efficient, Parameter-Free and Provably Stable Algorithm}, 
      author={Mazen Alamir},
      year={2026},
      eprint={2607.14600},
      archivePrefix={arXiv},
      primaryClass={cs.CE},
      url={https://arxiv.org/abs/2607.14600}, 
}