How should I enter systems of equations as index notation? - Mathematica Stack Exchange most recent 30 from mathematica.stackexchange.com 2019-09-18T14:46:11Z https://mathematica.stackexchange.com/feeds/question/201073 https://creativecommons.org/licenses/by-sa/4.0/rdf https://mathematica.stackexchange.com/q/201073 1 How should I enter systems of equations as index notation? Nolan King https://mathematica.stackexchange.com/users/57980 2019-06-27T04:03:15Z 2019-06-27T04:03:15Z <p>I'm trying to numerically solve a system of ODEs that I've worked out in index notation where it's not clear to me what the matrix representation of many terms would be, and writing each scalar equation individually seems impractical. </p> <p>For example one of the equations in Latex is </p> <p><span class="math-container">$$\dot{q}_i = \frac{p_i}{m} -\frac{{A}_i(q)}{m} - \frac{\hbar}{4m} \mathcal{B}_{jk}^{-1} D^2_{kj} {A}_i(q) \\$$</span></p> <p>where q,p and B are matrix valued functions I am solving for, and <span class="math-container">$D^2 A_i (q)$</span> is the Hessian matrix of <span class="math-container">$A_i(q)$</span>. </p> <p>What's the best strategy for putting this system in a representation Mathematica will understand? Is there and package for index notation support like this? </p>