Fourier

tests/test_utils.py → src/simpy/debug/test_utils.py

@@ -1,7 +1,7 @@
 from typing import Optional, Tuple, Union
 
 from simpy.debug.utils import debug_repr
-from simpy.expr import Expr, Symbol, TrigFunctionNotInverse, cast, log, symbols
+from simpy.expr import Expr, Float, Symbol, TrigFunctionNotInverse, cast, log, symbols
 from simpy.integration import integrate
 from simpy.simplify import expand_logs, trig_simplify
 
@@ -83,3 +83,14 @@ def unhashable_set_eq(a: list, b: list) -> bool:
         if el not in a:
             return False
     return True
+
+
+def eq_float(e1: Expr, e2: Expr, atol=1e-6):
+    if type(e1) != type(e2):
+        return False
+    if isinstance(e1, Float) and isinstance(e2, Float):
+        return abs(e1.value - e2.value) < atol
+
+    if not len(e1.children()) == len(e2.children()):
+        return False
+    return all(eq_float(c1, c2) for c1, c2 in zip(e1.children(), e2.children()))

src/simpy/equation.py

@@ -0,0 +1,37 @@
+from dataclasses import dataclass
+
+from .expr import Expr, Symbol
+
+
+@dataclass
+class Equation:
+    lhs: Expr
+    rhs: Expr
+
+
+def solve(equation: Equation, x: Symbol):
+    # Ensure the equation is set to 0 (ax + b = 0)
+    expr = equation.lhs - equation.rhs
+
+    # Initialize coefficients
+    coeff_a = 0
+    coeff_b = 0
+
+    # Iterate over the terms of the expression
+    for term in expr.as_terms():
+        if (term / x).symbolless:
+            coeff_a += term / x
+        elif not term.contains(x):
+            coeff_b += term
+        else:
+            raise NotImplementedError("can only solve linear eqs")
+
+    # Calculate the solution
+    if coeff_a == 0:
+        if coeff_b == 0:
+            return "Infinite solutions (identity equation)."
+        else:
+            return "No solution (contradictory equation)."
+
+    x_solution = -coeff_b / coeff_a
+    return x_solution