diff --git a/content/posts/hybrid-post.mdx b/content/posts/hybrid-post.mdx new file mode 100644 index 0000000..fdd99cd --- /dev/null +++ b/content/posts/hybrid-post.mdx @@ -0,0 +1,61 @@ +--- +title: "Fourier Analysis: From Math to Code" +date: "2025-03-10" +excerpt: "Bridging the gap between Fourier's mathematical theory and practical implementation." +--- + +Fourier analysis reveals a profound truth: any periodic function can be decomposed into a sum of simple sine and cosine waves. + +## The Math + +The Fourier series of a function $f(x)$ with period $2\pi$ is: + +$$f(x) = \frac{a_0}{2} + \sum_{n=1}^{\infty} \left( a_n \cos(nx) + b_n \sin(nx) \right)$$ + +where: + +$$a_n = \frac{1}{\pi} \int_{-\pi}^{\pi} f(x)\cos(nx)\,dx$$ + +$$b_n = \frac{1}{\pi} \int_{-\pi}^{\pi} f(x)\sin(nx)\,dx$$ + +## Python Implementation + +Let's approximate a square wave using the first few terms: + +```python +import numpy as np +import matplotlib.pyplot as plt + +def fourier_square_wave(x, n_terms): + """Approximate a square wave using Fourier series.""" + result = np.zeros_like(x) + for n in range(1, n_terms + 1, 2): # odd harmonics only + result += (4 / (n * np.pi)) * np.sin(n * x) + return result + +x = np.linspace(-np.pi, np.pi, 1000) +plt.figure(figsize=(10, 6)) +plt.plot(x, np.where(x >= 0, 1, -1), 'k--', label='Square wave') + +for terms in [1, 3, 7, 15]: + plt.plot(x, fourier_square_wave(x, terms), label=f'{terms} terms') + +plt.legend() +plt.title('Fourier Series Approximation of a Square Wave') +plt.grid(True, alpha=0.3) +plt.savefig('fourier.png', dpi=150) +``` + +## Understanding Convergence + +The Gibbs phenomenon shows that near discontinuities, the approximation overshoots by approximately: + +$$9\%$$ + +This is mathematically expressed as: + +$$\lim_{N \to \infty} \text{overshoot} \approx 1.08949 \times \text{jump}$$ + +## Conclusion + +The connection between the elegant mathematics and practical code demonstrates how theory informs implementation. Fourier analysis is the foundation of signal processing, image compression, and countless other applications.