2017-11-09 07:55:48 -0500 received badge ● Student (source) 2014-06-28 23:56:27 -0500 received badge ● Famous Question (source) 2014-06-28 23:56:27 -0500 received badge ● Popular Question (source) 2014-06-28 23:56:27 -0500 received badge ● Notable Question (source) 2013-01-22 10:40:02 -0500 received badge ● Scholar (source) 2013-01-22 10:40:02 -0500 marked best answer How to do symbolic computation with quaternions You should define Q as a QuaternionAlgebra over the symbolic ring SR instead of over the rationals: sage: Q. = QuaternionAlgebra(SR, -1, -1) sage: q = a*i + b*j + c*k sage: q a*i + b*j + c*k sage: q^2 -a^2 - b^2 - c^2  2013-01-21 20:37:05 -0500 asked a question How to do symbolic computation with quaternions I need to do symbolic computations with quaternions. Ideally I'd like to enter something like Q. = QuaternionAlgebra(QQ,-1,-1) a=var('a') b=var('b') c=var('c') q = a*i+b*j+c*k  But it doesn't work : TypeError: unsupported operand parent(s) for '*': 'Symbolic Ring' and 'Quaternion Algebra (-1, -1) with base ring Rational Field' Looks like SAGE doesn't know how to multiply a variable and a quaternion. Or should I specify the types of the variables ? How ? Thanks for your help.