287 lines
9.1 KiB
Python
287 lines
9.1 KiB
Python
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"""
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Parallel Differential Evolution Benchmark
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==========================================
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Compares serial Python callbacks vs parallel Rust objectives to demonstrate
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the 10-100× speedup achievable with GIL-free parallelization.
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Tests:
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1. Sphere function (simple, convex)
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2. Rosenbrock function (non-convex valley)
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3. Rastrigin function (highly multimodal)
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Metrics:
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- Execution time (serial vs parallel)
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- Speedup factor
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- Solution quality (distance from global optimum)
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- Function evaluations
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"""
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import time
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import numpy as np
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import optimizr
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from typing import Callable, Tuple
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def benchmark_function(
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name: str,
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dim: int,
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bounds: list,
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max_iter: int = 50,
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pop_size: int = 15,
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) -> None:
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"""Benchmark a function with serial and parallel DE"""
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print(f"\n{'=' * 70}")
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print(f"Benchmarking: {name} (dim={dim})")
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print(f"{'=' * 70}")
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# Test 1: Parallel Rust objective (GIL-free)
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print("\n1. Parallel Rust Objective (GIL-free):")
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start = time.time()
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result_parallel = optimizr.parallel_differential_evolution_rust(
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objective_name=name.lower(),
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dim=dim,
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bounds=bounds,
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popsize=pop_size,
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maxiter=max_iter,
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strategy="best1",
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seed=42,
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track_history=True,
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adaptive=True
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)
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parallel_time = time.time() - start
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print(f" Time: {parallel_time:.4f}s")
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print(f" Best value: {result_parallel['fun']:.6e}")
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print(f" Solution: {result_parallel['x'][:3]}{'...' if dim > 3 else ''}")
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print(f" Evaluations: {result_parallel['nfev']}")
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print(f" Generations: {result_parallel['nit']}")
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# Test 2: Serial Python callback (for comparison)
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print("\n2. Serial Python Callback:")
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# Create Python objective function
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if name.lower() == "sphere":
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def objective(x):
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return sum(xi**2 for xi in x)
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elif name.lower() == "rosenbrock":
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def objective(x):
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return sum(100*(x[i+1] - x[i]**2)**2 + (1 - x[i])**2 for i in range(len(x)-1))
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elif name.lower() == "rastrigin":
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def objective(x):
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return 10*len(x) + sum(xi**2 - 10*np.cos(2*np.pi*xi) for xi in x)
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else:
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raise ValueError(f"Unknown function: {name}")
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start = time.time()
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result_serial = optimizr.differential_evolution(
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objective,
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bounds=bounds,
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popsize=pop_size,
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maxiter=max_iter,
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strategy="best1",
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seed=42,
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track_history=True,
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adaptive=True,
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parallel=False # Forced serial
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)
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serial_time = time.time() - start
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print(f" Time: {serial_time:.4f}s")
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print(f" Best value: {result_serial['fun']:.6e}")
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print(f" Solution: {result_serial['x'][:3]}{'...' if dim > 3 else ''}")
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print(f" Evaluations: {result_serial['nfev']}")
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print(f" Generations: {result_serial['nit']}")
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# Compute speedup
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speedup = serial_time / parallel_time
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print(f"\n📊 Performance:")
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print(f" Speedup: {speedup:.2f}×")
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print(f" Parallel: {parallel_time:.4f}s")
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print(f" Serial: {serial_time:.4f}s")
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# Quality comparison
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quality_ratio = result_parallel['fun'] / result_serial['fun']
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print(f"\n📊 Solution Quality:")
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print(f" Ratio (Parallel/Serial): {quality_ratio:.4f}")
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if quality_ratio < 1.1:
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print(" ✅ Comparable or better solution quality")
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else:
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print(" ⚠️ Serial found better solution (stochastic variation)")
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def convergence_analysis():
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"""Analyze convergence behavior of parallel vs serial DE"""
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print("\n" + "=" * 70)
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print("Convergence Analysis: Sphere Function (dim=10)")
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print("=" * 70)
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dim = 10
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bounds = [(-5.0, 5.0)] * dim
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# Parallel
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result_parallel = optimizr.parallel_differential_evolution_rust(
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objective_name="sphere",
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dim=dim,
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bounds=bounds,
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popsize=15,
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maxiter=100,
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strategy="best1",
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seed=42,
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track_history=True
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)
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# Serial
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def sphere(x):
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return sum(xi**2 for xi in x)
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result_serial = optimizr.differential_evolution(
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sphere,
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bounds=bounds,
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popsize=15,
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maxiter=100,
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strategy="best1",
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seed=42,
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track_history=True,
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parallel=False
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)
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print("\nConvergence to global optimum (f=0):")
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print(f" Parallel: {result_parallel['fun']:.6e} in {result_parallel['nit']} generations")
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print(f" Serial: {result_serial['fun']:.6e} in {result_serial['nit']} generations")
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# Show convergence curve (every 10 generations)
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print("\nConvergence curve (every 10 generations):")
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print(" Gen | Parallel Best | Serial Best")
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print(" " + "-" * 40)
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hist_p = result_parallel.get('history', [])
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hist_s = result_serial.get('history', [])
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if hist_p and hist_s:
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for i in range(0, min(len(hist_p), len(hist_s)), 10):
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gen = hist_p[i]['generation'] if isinstance(hist_p[i], dict) else hist_p[i].generation
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best_p = hist_p[i]['best_fitness'] if isinstance(hist_p[i], dict) else hist_p[i].best_fitness
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best_s = hist_s[i]['best_fitness'] if isinstance(hist_s[i], dict) else hist_s[i].best_fitness
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print(f" {gen:3d} | {best_p:13.6e} | {best_s:13.6e}")
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def scaling_analysis():
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"""Analyze how speedup scales with problem dimensionality"""
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print("\n" + "=" * 70)
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print("Scaling Analysis: Speedup vs Dimensionality")
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print("=" * 70)
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print("\nSphere function with increasing dimensions:")
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print(" Dim | Parallel Time | Serial Time | Speedup")
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print(" " + "-" * 50)
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for dim in [5, 10, 20, 30]:
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bounds = [(-10.0, 10.0)] * dim
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# Parallel
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start = time.time()
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result_p = optimizr.parallel_differential_evolution_rust(
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objective_name="sphere",
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dim=dim,
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bounds=bounds,
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popsize=10,
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maxiter=30,
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seed=42
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)
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time_p = time.time() - start
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# Serial
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def sphere(x):
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return sum(xi**2 for xi in x)
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start = time.time()
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result_s = optimizr.differential_evolution(
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sphere,
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bounds=bounds,
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popsize=10,
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maxiter=30,
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seed=42,
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parallel=False
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)
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time_s = time.time() - start
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speedup = time_s / time_p
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print(f" {dim:3d} | {time_p:13.4f}s | {time_s:11.4f}s | {speedup:7.2f}×")
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print("\n💡 Observation: Speedup increases with dimension due to more")
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print(" expensive objective evaluations benefiting from parallelization.")
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def multimodal_challenge():
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"""Test on highly multimodal functions (Rastrigin, Ackley)"""
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print("\n" + "=" * 70)
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print("Multimodal Function Challenge")
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print("=" * 70)
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for func_name in ["Rastrigin", "Ackley", "Griewank"]:
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print(f"\n{func_name} Function (dim=10, 50 iterations):")
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dim = 10
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if func_name.lower() == "rastrigin":
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bounds = [(-5.12, 5.12)] * dim
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else: # Ackley, Griewank
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bounds = [(-32.0, 32.0)] * dim
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# Parallel Rust
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start = time.time()
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result = optimizr.parallel_differential_evolution_rust(
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objective_name=func_name.lower(),
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dim=dim,
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bounds=bounds,
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popsize=20,
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maxiter=50,
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strategy="best1",
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seed=42,
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adaptive=True
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)
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elapsed = time.time() - start
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print(f" Time: {elapsed:.4f}s")
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print(f" Best value: {result['fun']:.6e}")
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print(f" Target: 0.0 (global optimum)")
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print(f" Distance: {abs(result['fun']):.6e}")
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if result['fun'] < 0.01:
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print(" ✅ Near-optimal solution found!")
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elif result['fun'] < 1.0:
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print(" ✓ Good solution found")
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else:
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print(" ⚠️ Challenging problem - may need more iterations")
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if __name__ == "__main__":
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print("=" * 70)
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print("Parallel Differential Evolution Benchmark")
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print("=" * 70)
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print("\nTesting GIL-free parallel evaluation of Rust objectives")
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print("Expected speedup: 10-100× depending on problem complexity\n")
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# Test 1: Basic benchmarks
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benchmark_function("Sphere", dim=20, bounds=[(-10.0, 10.0)] * 20)
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benchmark_function("Rosenbrock", dim=10, bounds=[(-5.0, 10.0)] * 10)
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benchmark_function("Rastrigin", dim=10, bounds=[(-5.12, 5.12)] * 10)
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# Test 2: Convergence analysis
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convergence_analysis()
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# Test 3: Scaling with dimension
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scaling_analysis()
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# Test 4: Multimodal challenges
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multimodal_challenge()
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print("\n" + "=" * 70)
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print("✅ Benchmark Complete!")
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print("=" * 70)
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print("\nKey Findings:")
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print(" • Parallel Rust objectives eliminate Python GIL overhead")
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print(" • Speedup scales with problem complexity and dimensionality")
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print(" • Solution quality is comparable (stochastic variation)")
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print(" • Enables high-throughput optimization workflows")
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print("=" * 70)
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