chan_vese: pass all constants to _fused_variance_kernel2 as device …

…scalars (#764)

This change avoids an issue with an internal `numpy.can_cast` call in CuPy's kernel fusion code when using NumPy 2.0. With this change all cuCIM tests passed using NumPy 2.0.1 and the CuPy 13.3dev branch.

Fixes #742

Authors:
  - Gregory Lee (https://github.com/grlee77)

Approvers:
  - https://github.com/jakirkham
  - Gigon Bae (https://github.com/gigony)

URL: #764

python/cucim/src/cucim/skimage/segmentation/_chan_vese.py

@@ -65,7 +65,9 @@ def _fused_variance_kernel2(
     difference_term += term2
 
     new_phi = phi + (dt * delta_phi) * (mu * K + difference_term)
-    out = new_phi / (1 + mu * dt * delta_phi * Csum)
+    out_denom = mu * dt * delta_phi * Csum
+    out_denom += out_denom.dtype.type(1)
+    out = new_phi / out_denom
     return out
 
 
@@ -430,6 +432,9 @@ def chan_vese(
     phivar = tol + 1
 
     dt = cp.asarray(dt, dtype=float_dtype)
+    mu = cp.asarray(mu, dtype=float_dtype)
+    lambda1 = cp.asarray(lambda1, dtype=float_dtype)
+    lambda2 = cp.asarray(lambda2, dtype=float_dtype)
     while phivar > tol and i < max_num_iter:
         # Save old level set values
         oldphi = phi