fix(ga): Derivative of a constant now returns 0 instead of a throwing an error

pyproject.toml

@@ -5,7 +5,7 @@ build-backend = "setuptools.build_meta"
 [project]
 # --- Core Metadata ---
 name = "polysolve"
-version = "0.6.0"
+version = "0.6.1"
 authors = [
   { name="Jonathan Rampersad", email="jonathan@jono-rams.work" },
 ]

src/polysolve/__init__.py

@@ -133,6 +133,15 @@ class GA_Options:
             raise ValueError(
                 f"blend_alpha cannot be negative, but got {self.blend_alpha}"
             )
+        if self.root_precision > 15:
+            warnings.warn(
+                f"root_precision={self.root_precision} is greater than 15. "
+                "This demands an accuracy that is likely impossible for standard "
+                "64-bit floats (float64), which are limited to 15-16 significant digits. "
+                "The solver may fail to find any roots.",
+                UserWarning,
+                stacklevel=2
+            )
 
 def _get_cauchy_bound(coeffs: np.ndarray) -> float:
     """
@@ -256,7 +265,9 @@ class Function:
         """
         self._check_initialized()
         if self._largest_exponent == 0:
-            raise ValueError("Cannot differentiate a constant (Function of degree 0).")
+            diff_func = Function(0)
+            diff_func.set_coeffs([0])
+            return diff_func
         
         derivative_coefficients = np.polyder(self.coefficients)
         
@@ -672,7 +683,7 @@ class Function:
     
     def _multiply_by_scalar(self, scalar: Union[int, float]) -> 'Function':
         """Helper method to multiply the function by a scalar constant."""
-        self._check_initialized() # It's good practice to check here too
+        self._check_initialized()
 
         if scalar == 0:
             result_func = Function(0)