Changed default behaviouf of create_vector_homog

3D now always has 3 components, 2D only if theta is specified!

src/empyre/fields/vectors.py

@@ -37,11 +37,13 @@ def create_vector_homog(dim, phi=0, theta=None, scale=1.0):
     assert len(dim) in (2, 3), 'Disc can only be build in 2 or 3 dimensions!'
     assert isinstance(phi, Number), 'phi has to be an angle in radians!'
     assert isinstance(theta, Number) or theta is None, 'theta has to be an angle in radians or None!'
-    if theta is None:
+    if len(dim) == 2 and theta is None:  # 2D and 3rd component not explicitely wanted:
         y_comp = np.ones(dim) * np.sin(phi)
         x_comp = np.ones(dim) * np.cos(phi)
         data = np.stack([x_comp, y_comp], axis=-1)
-    else:
+    else:  # 3D, always have a third component:
+        if theta is None:
+            theta = np.pi/2  # xy-plane if not specified otherwise!
         z_comp = np.ones(dim) * np.cos(theta)
         y_comp = np.ones(dim) * np.sin(theta) * np.sin(phi)
         x_comp = np.ones(dim) * np.sin(theta) * np.cos(phi)