Time derivative then partial derivative of symbolic function

In the following code I would like to take the time derivative and then the partial derivative to x and/or y of a symbolic function.

syms x(t) y(t)
f = 4*x^3 + 3*y^2;
g = diff(f,t);
h = diff(g,x(t));

In line 4 an error tells me "Second argument must be a variable or a nonnegative integer specifying the number of differentiations."

How can I alter my code such that I can take this partial derivative?

Answer 1

[Star Strider]

Just do:

h = diff(g,x);

and it works.

[Lauran Leermakers]

Then it gives me another error

"Arguments, except for the first, must not be symbolic functions."

[Star Strider]

Interesting. It runs without error in R2020b, and produces:

h(t) =
24*x(t)*diff(x(t), t)

I can only suggest upgrading to R2020b, since I cannot reproduce that problem so cannot experiment with it.

[Lauran Leermakers]

Then you for your help. I will try to upgrade to R202b

[Star Strider]

My pleasure.

First, be certain that you have the latest Update to R2020a. This improvement could have been included in the Updates.

[Lauran Leermakers]

I have succesfully upgraded to R2020b. Your suggestion works now! Thanks again

[Star Strider]

As always, my pleasure!