feat(FXC-4519): Added check to warn of duplicated voltage values

Author: marc-flex

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- Added validation to `DCVoltageSource` that warns when duplicate voltage values are detected in the `voltage` array, including treating `0` and `-0` as the same value.
 
 ### Changed
 

tests/test_components/test_heat_charge.py

@@ -903,6 +903,25 @@ def test_heat_charge_bcs_validation(boundary_conditions):
         td.VoltageBC(source=td.SSACVoltageSource(voltage=np.array([td.inf, 0, 1]), amplitude=1e-2))
 
 
+def test_repeated_voltage_warning():
+    """Test that a warning is raised when repeated voltage values are present."""
+    # No warning for unique values
+    with AssertLogLevel(None):
+        td.DCVoltageSource(voltage=[0, 1, 2, 3])
+
+    # Warning for repeated values
+    with AssertLogLevel("WARNING"):
+        td.DCVoltageSource(voltage=[1, 2, 2, 3])
+
+    # Warning for 0 and -0 (treated as duplicates)
+    with AssertLogLevel("WARNING"):
+        td.DCVoltageSource(voltage=[0.0, -0.0, 1, 2])
+
+    # Warning for multiple repeated values
+    with AssertLogLevel("WARNING"):
+        td.DCVoltageSource(voltage=[1, 1, 2, 2, 3])
+
+
 def test_freqs_validation():
     """Test validation that freqs requires SSACVoltageSource."""
     solid_box_1 = td.Box(center=(0, 0, 0), size=(2, 2, 2))

tidy3d/components/spice/sources/dc.py

@@ -23,12 +23,14 @@
 
 from typing import Literal, Optional
 
+import numpy as np
 import pydantic.v1 as pd
 
 from tidy3d.components.base import Tidy3dBaseModel
 from tidy3d.components.types import ArrayFloat1D
 from tidy3d.constants import AMP, VOLT
 from tidy3d.constants import inf as td_inf
+from tidy3d.log import log
 
 
 class DCVoltageSource(Tidy3dBaseModel):
@@ -73,6 +75,20 @@ def check_voltage(cls, val):
                 raise ValueError(f"Voltages must be finite. Currently  voltage={val}.")
         return val
 
+    @pd.validator("voltage")
+    def check_repeated_voltage(cls, val):
+        """Warn if repeated voltage values are present, treating 0 and -0 as the same value."""
+        # Normalize all zero values (both 0.0 and -0.0) to 0.0 so they are treated as duplicates
+        normalized = np.where(val == 0, 0.0, val)
+        unique_values = np.unique(normalized)
+        if len(unique_values) < len(val):
+            log.warning(
+                "Duplicate voltage values detected in 'voltage' array. "
+                f"Found {len(val)} values but only {len(unique_values)} are unique. "
+                "Note: 0 and -0 are considered the same value."
+            )
+        return val
+
 
 class GroundVoltage(Tidy3dBaseModel):
     """