Delete arithmetic_analysis/ directory and relocate its contents (#10824)

* Remove eval from arithmetic_analysis/newton_raphson.py

* Relocate contents of arithmetic_analysis/

Delete the arithmetic_analysis/ directory and relocate its files because
the purpose of the directory was always ill-defined. "Arithmetic
analysis" isn't a field of math, and the directory's files contained
algorithms for linear algebra, numerical analysis, and physics.

Relocated the directory's linear algebra algorithms to linear_algebra/,
its numerical analysis algorithms to a new subdirectory called
maths/numerical_analysis/, and its single physics algorithm to physics/.

* updating DIRECTORY.md

---------

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

maths/numerical_analysis/secant_method.py

@@ -0,0 +1,29 @@
+"""
+Implementing Secant method in Python
+Author: dimgrichr
+"""
+from math import exp
+
+
+def f(x: float) -> float:
+    """
+    >>> f(5)
+    39.98652410600183
+    """
+    return 8 * x - 2 * exp(-x)
+
+
+def secant_method(lower_bound: float, upper_bound: float, repeats: int) -> float:
+    """
+    >>> secant_method(1, 3, 2)
+    0.2139409276214589
+    """
+    x0 = lower_bound
+    x1 = upper_bound
+    for _ in range(repeats):
+        x0, x1 = x1, x1 - (f(x1) * (x1 - x0)) / (f(x1) - f(x0))
+    return x1
+
+
+if __name__ == "__main__":
+    print(f"Example: {secant_method(1, 3, 2)}")