I want to differentiate a function
f for which I don't have a specific expression.
f depends on
y and has parameters k1 and k2 in it.
y depend on
t,and not on
So when I use the total derivation operator
Dt[f, t], only
y should be differentiated.
But how can I say Mathematica that k1 and k2 are constant, without assigning values to them?