Can I use d/dt or overdot notation for symbolic equations?

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cdlapoin 2022-9-7

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回答： Beck 2025-9-24

Using symbolic equations Matlab does some handy stuff like converting theta_1 to the greek symbol with the appropriate subscript. Is there a way to convert a derivative the same way? So that it will display as dtheta/dt or with an overdot (latex: \dot{\theta})?

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cdlapoin 2022-9-7

Thanks @John D'Errico and @Star Strider that answers my question.

The reason I am using a live script in this case is to report the solutions to other people. Being able to tidy up the output like this saves me from having to restate everything with LateX equations. It is just fluff, but fluff is important sometimes!

Star Strider 2022-9-7

@casey lapoint — Consider using the latex function. It could make things easier.

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采纳的回答

Beck 2025-9-24

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Define your derivative variables in your syms call, then use subs() to swap the symbols in the display:

syms theta(t) theta_dot
x = theta
y = diff(x,t)
y = subs(y,diff(theta,t), theta_dot)

If you have a lot of symbols to replace, use sets. Just be careful of the order in which you replace symbols: you should go from highest order derivative to lowest.

syms theta(t) theta_dot theta_ddot omega(t) omega_dot omega_ddot
x = omega + theta;
y = diff(x,t);
z = diff(x,t,t);
oldsyms = {diff(theta,t,t), diff(omega,t,t), diff(theta,t), diff(omega,t)};
newsyms = {theta_ddot, omega_ddot, theta_dot, omega_dot};
y = subs(y, oldsyms, newsyms)
z = subs(z, oldsyms, newsyms)