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Fix/twist pitch clean #196

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Fix/twist pitch clean #196

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beef079
fix(twist): add missing denominator in Twist3.pitch calculation
petercorke Jul 27, 2026
3b97759
test(twist): add regression test for pitch denominator fix
petercorke Jul 27, 2026
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2 changes: 1 addition & 1 deletion spatialmath/twist.py
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Original file line number Diff line number Diff line change
Expand Up @@ -945,7 +945,7 @@ def pitch(self):
>>> S.pitch

"""
return np.dot(self.w, self.v)
return np.dot(self.w, self.v) / np.dot(self.w, self.w)

def line(self):
"""
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11 changes: 11 additions & 0 deletions tests/test_twist.py
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Expand Up @@ -179,6 +179,17 @@ def test_exp(self):
tw = Twist3.UnitRevolute([0, 0, 1], [0, 0, 0])
array_compare(tw.exp(pi / 2), SE3.Rz(pi / 2))

def test_pitch(self):
# pitch = (w . v) / (w . w), regression test for missing denominator

# non-unit w: exercises the normalization, would fail without it
tw = Twist3([0, 0, 4], [0, 0, 2])
self.assertAlmostEqual(tw.pitch, 2.0)

# unit w: denominator is 1, sanity check against UnitRevolute's pitch arg
tw = Twist3.UnitRevolute([0, 0, 1], [0, 0, 0], pitch=3)
self.assertAlmostEqual(tw.pitch, 3.0)

def test_arith(self):
# check overloaded *

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