added readme information for pi

docs/pi.md

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+## Approximating Pi Using Numerical Summation
+
+### Explanation
+This method approximates the value of \( \pi \) using a numerical summation technique. The approach is based on the concept of inscribing and circumscribing rectangles under a quarter-circle to estimate the area. By summing the areas of these rectangles, we can approximate the area of the quarter-circle, which in turn helps us estimate \( \pi \).
+
+### Mathematical Representation
+The equation used is:
+
+![Pi Equation](.../.././base.png)
+
+Where:
+- \( a \) and \( b \) are summations that approximate the quarter-circle area.
+- The sum iterates over a set of discrete steps to refine the approximation.
+
+More specifically, \( a \) and \( b \) are defined as:
+
+![A Equation](.../.././a.png)
+
+![B Equation](.../.././b.png)
+
+### Python Equivalent
+
+```python file.py
+import math
+
+def approximate_pi(n=46325):
+    lange = n - 2
+    a, b = 0, 0
+
+    # Compute summation for 'a'
+    for k in range(1, lange + 1):  # Changed to include lange
+        a += math.sqrt(n**2 - k**2)
+
+    # Compute summation for 'b'
+    for j in range(lange + 1):  # Changed to include lange
+        b += math.sqrt(n**2 - j**2)
+
+    # Normalize the results
+    b = 4 / (n**2) * b
+    a = 4 / (n**2) * a
+    result = (a + b) / 2
+
+    return result
+
+# Run the function
+print(approximate_pi())
+```
+
+### How It Works
+1. **Initialization**: The variable `lange` is set to \( n - 2 \), and two summation variables `a` and `b` are initialized to zero.
+2. **Summation for 'a'**: Iterates from 1 to `lange`, calculating the square root of \( n^2 - k^2 \) for each \( k \).
+3. **Summation for 'b'**: Iterates from 0 to `lange`, calculating the square root of \( n^2 - j^2 \) for each \( j \).
+4. **Normalization**: Both summations are normalized by multiplying by \( \frac{4}{n^2} \).
+5. **Result Calculation**: The final approximation of \( \pi \) is obtained by averaging the normalized values of `a` and `b`.
+
+### Conclusion
+This method provides an approximation of \( \pi \) using numerical summation. The accuracy increases as \( n \) grows larger, effectively refining the result. By adjusting the value of \( n \), you can control the trade-off between computational effort and precision.
+
+### Notes
+- The choice of `n = 46325` is arbitrary and can be adjusted for better performance or higher precision.
+- This method is computationally intensive and may require optimization for very large values of \( n \).