fix meshgrid indexing

fresnel/misc.py

@@ -28,7 +28,7 @@ def fftfreqn(n, dx=1):
 
     xi = [fftfreq(n_i, dx_i) for n_i, dx_i in zip(n, dx)]
 
-    return np.meshgrid(*xi, sparse=True)
+    return np.meshgrid(*xi, sparse=True, indexing='ij')
 
 
 def gridn(n):
@@ -37,7 +37,7 @@ def gridn(n):
 
     x = [np.arange(-n[dim] + 1, n[dim]) for dim in range(ndim)]
 
-    return np.meshgrid(*x, sparse=True)
+    return np.meshgrid(*x, sparse=True, indexing='ij')
 
 
 def crop(a, crop_width):