fix bug in event function resolver

dysts/systems.py

@@ -21,11 +21,10 @@
     DynSys,
     DynSysDelay,
 )
+from .utils import num_unspecified_params
 
 Array = npt.NDArray[np.float64]
 
-DEFAULT_RNG = np.random.default_rng()
-
 
 def get_attractor_list(
     sys_class: str = "continuous", exclude: list[str] = []
@@ -118,7 +117,7 @@ def _resolve_event_signature(
     Returns:
         The resolved event function (solve_ivp compatible)
     """
-    if len(inspect.signature(event).parameters) == 1:
+    if num_unspecified_params(event) == 1:
         return event(system)  # type: ignore
     return event  # type: ignore
 

dysts/utils/native_utils.py

@@ -6,6 +6,37 @@
 import os
 import threading
 import warnings
+from inspect import Parameter, signature
+
+
+def num_unspecified_params(func) -> int:
+    """Count required parameters that haven't been specified through partial or defaults.
+
+    Args:
+        func: Function or partial function to inspect
+
+    Returns:
+        Number of parameters that must be specified when calling the function
+    """
+    if hasattr(func, "func"):  # Check if partial
+        partial_func = func.func
+        partial_args = len(func.args)
+        partial_keywords = func.keywords or {}
+    else:
+        partial_func = func
+        partial_args = 0
+        partial_keywords = {}
+
+    sig = signature(partial_func)
+    required_count = 0
+
+    for i, (name, param) in enumerate(sig.parameters.items()):
+        if i < partial_args or name in partial_keywords:
+            continue
+        if param.default == Parameter.empty:
+            required_count += 1
+
+    return required_count
 
 
 def has_module(module_name: str) -> bool: