fixed winding surface issue

src/simsopt/geo/curveobjectives.py

@@ -260,11 +260,15 @@ def ws_distance_pure(gammac, lc, gammas, ns, maximum_distance):
     This function is used in a Python+Jax implementation of the curve-surface distance
     formula.
     """
+    nss = gammas.size
+    ncc = gammac.size
     dists = jnp.sqrt(jnp.sum(
         (gammac[:, None, :] - gammas[None, :, :])**2, axis=2))
     integralweight = jnp.linalg.norm(lc, axis=1)[:, None] \
         * jnp.linalg.norm(ns, axis=1)[None, :]
-    return jnp.mean(integralweight * jnp.maximum(dists-maximum_distance, 0)**2)
+    return jnp.mean(
+        integralweight * jnp.maximum(dists**2-maximum_distance**2, 0)**2
+        ) / (nss*ncc)**2
 
 class WindingSurface(Optimizable):
     r"""Used to constrain coils to remain on a surface