From 6758a3ccbca1dd27ebe146f2032b5dc162284a0f Mon Sep 17 00:00:00 2001
From: daniel-dudt <daniel.dudt@princetonstellarators.energy>
Date: Mon, 19 Aug 2024 17:11:26 -0600
Subject: [PATCH] allow QuadraticFlux to take multiple fields

---
 desc/objectives/_coils.py | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/desc/objectives/_coils.py b/desc/objectives/_coils.py
index 62ef664622..bfc5e0d548 100644
--- a/desc/objectives/_coils.py
+++ b/desc/objectives/_coils.py
@@ -1175,12 +1175,11 @@ def __init__(
         self._source_grid = source_grid
         self._eval_grid = eval_grid
         self._eq = eq
-        self._field = field
+        self._field = [field] if not isinstance(field, list) else field
         self._field_grid = field_grid
         self._vacuum = vacuum
-        things = [field]
         super().__init__(
-            things=things,
+            things=self._field,
             target=target,
             bounds=bounds,
             weight=weight,
@@ -1200,6 +1199,8 @@ def build(self, use_jit=True, verbose=1):
             Level of output.
 
         """
+        from desc.magnetic_fields import SumMagneticField
+
         eq = self._eq
 
         if self._eval_grid is None:
@@ -1241,7 +1242,7 @@ def build(self, use_jit=True, verbose=1):
             )
 
         self._constants = {
-            "field": self._field,
+            "field": SumMagneticField(self._field),
             "field_grid": self._field_grid,
             "quad_weights": w,
             "eval_data": eval_data,
@@ -1258,7 +1259,7 @@ def build(self, use_jit=True, verbose=1):
 
         super().build(use_jit=use_jit, verbose=verbose)
 
-    def compute(self, field_params, constants=None):
+    def compute(self, *field_params, constants=None):
         """Compute boundary force error.
 
         Parameters