Schwefel Function Surface

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.colors import LinearSegmentedColormap

x = np.linspace(-500, 500, 200)
y = np.linspace(-500, 500, 200)
X, Y = np.meshgrid(x, y)

Z = 418.9829 * 2 - X * np.sin(np.sqrt(np.abs(X))) - Y * np.sin(np.sqrt(np.abs(Y)))

fig, ax = plt.subplots(figsize=(10, 8), facecolor='#ffffff')
ax.set_facecolor('#ffffff')

# Deep purple to pink
colors = ['#faf5ff', '#d8b4fe', '#a855f7', '#5314E6']
cmap = LinearSegmentedColormap.from_list('purple', colors, N=256)

cs = ax.contourf(X, Y, Z, levels=30, cmap=cmap)
ax.contour(X, Y, Z, levels=15, colors='#581c87', linewidths=0.4, alpha=0.5)
cbar = plt.colorbar(cs, ax=ax, pad=0.02)
cbar.set_label('f(x,y)', color='#374151', fontsize=11)
cbar.ax.yaxis.set_tick_params(color='#374151')
plt.setp(plt.getp(cbar.ax.axes, 'yticklabels'), color='#374151')

ax.set_xlabel('X', fontsize=11, color='#374151', fontweight='500')
ax.set_ylabel('Y', fontsize=11, color='#374151', fontweight='500')
ax.set_title('Schwefel Function Surface', fontsize=14, color='#1f2937', fontweight='bold', pad=15)

ax.tick_params(colors='#6b7280', labelsize=9)
for spine in ax.spines.values():
    spine.set_color('#d1d5db')

plt.tight_layout()
plt.show()