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# Quaternion angle with itself > 0.001

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### #21Álvaro  Members

Posted 13 August 2014 - 11:30 AM

You can also compute the angle between quaternions using
  dot_product = dot4(qa, qb);
dot_product_squared = dot_product * dot_product;
denominator = dot4(qa, qa) * dot4(qb, qb);
return 2.0f * acos(sqrt(abs(dot_product_squared / denominator)));
I haven't tried it, so there could be mistakes. The idea is to not rely on the inputs being normalized, and write the expression in such a way that you are guaranteed to get exactly 0 if you qa==qb.

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