Can I derive a dependent variable in Matlab?

Ex. 
y=x(t) so that y'=x'(t)

[Walter Roberson]

Please give more context? Your tag "system modeling" suggests that you are not talking about the Symbolic Toolbox?

Answer 1

[Koushik Vemula]

According to my understanding you want to create a variable ‘y’ which is dependent on variable ‘x’

You can do it using ‘syms’ module.

Creating variable ‘y’ dependent on ‘t’

syms y t   %defining  y and t as variables 
y=t*t + 3  %for example 
diff(y) 

Here the function ‘diff’ represents differentiation of the variable y.

For more understanding of the module ‘syms’ refer this link: https://www.mathworks.com/help/symbolic/syms.html