bugfix: fix div/0 err in quat->unit vec conversion

Addresses portion of #19
flatironinstitute · Dec 7, 2023 · daf142f · daf142f
1 parent f29c537
commit daf142f
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/ManifoldEM/GetDistancesS2.py b/ManifoldEM/GetDistancesS2.py
@@ -82,7 +82,10 @@ def quats_to_unit_vecs(q: NDArray[Shape["4,*"], Float64]) -> NDArray[Shape["3,*"
 def get_psi(q: NDArray[Shape["4"], Float64], ref_vec: NDArray[Shape["3"], Float64]) -> float:
     s = -(1 + ref_vec[2]) * q[3] - ref_vec[0] * q[1] - ref_vec[1] * q[2]
     c = (1 + ref_vec[2]) * q[0] + ref_vec[1] * q[1] - ref_vec[0] * q[2]
-    psi = 2 * np.arctan(s / c)  # note that the Psi are in the interval [-pi,pi]
+    if c == 0.0:
+        psi = np.sign(s) * np.pi
+    else:
+        psi = 2 * np.arctan(s / c)  # note that the Psi are in the interval [-pi,pi]
 
     return psi