What is Nostr?
Shane Celis /
npub1lyl…3dml
2023-10-21 21:50:27
in reply to nevent1q…gsl4

Shane Celis on Nostr: npub14yqjk…vrfl3 But why multiply twice? Well, when you multiple a regular vector p ...

npub14yqjkzqkgv4a27egvq5xmh2ravemytg9g5kldqeqfts92uvh90sq2vrfl3 (npub14yq…rfl3) But why multiply twice? Well, when you multiple a regular vector p with a quaternion, you project it into quaternion space P = 0 + px i + py j + pz k. Notice the real part is zero. In general when you multiply a quaternion and a vector, you don’t get back a vector; you get another quaternion; its real part is not zero. However when you do q P q^-1, you’re guaranteed to get a vector; the real part will be zero. But it is effectively rotating it twice, so that’s why use half angles.
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npub1lyl9nhvpfjgyf76xe6qm2v38sxxftz0y097cq86rn7zd4jtpndas2s3dml