CODEWITHSUNDEEP
maple
Arnold Schwarzenegger
Arnold Schwarzenegger

Reputation: 99

How to declare a generic variable as a function of time in Maplesoft so that chainrule can be applied?

I hope someone could give me some help on using Maple for symbolic computation.

Below is my code to declare a generic variable eta as a function of time: enter image description here

I notice that when I differentiate eta with respect to time , 0 is returned. However, what I would like to have is eta_dot. Ultimately I would like to take the time derivative of column matrix at the very bottom in the screenshot above. How should I acheive this?

Upvotes: 0

Views: 534

Answers (1)

acer
acer

Reputation: 7271

Your first line,

eta := t -> eta

is meaningless, and should be removed (to avoid it confusing things).

Elsewhere, if you intended eta to represent an (unspecified/placeholder) expression in t you should be using eta(t) instead.

For example,

restart;
# examples with unspecified functions of t

eta(t);

          eta(t)

diff(eta(t), t);

          d        
         --- eta(t)
          dt       

expr1 := sin(eta(t));

          expr1 := sin(eta(t))

diff(expr1, t);

       / d        \            
       |--- eta(t)| cos(eta(t))
       \ dt       /            

expr2 := sin(eta(t)) * cos(beta(t));

   expr2 := sin(eta(t)) cos(beta(t))

diff(expr2, t);

   / d        \                         
   |--- eta(t)| cos(eta(t)) cos(beta(t))
   \ dt       /                         

                   / d         \             
     - sin(eta(t)) |--- beta(t)| sin(beta(t))
                   \ dt        /

You didn't explain what that Vector represents, so that part of you question is unclear. I will mention that I see what look like several missing multiplication signs (explicit *, or implicit space to denote that) in your 2D Math image. I suggest you be very careful with that, and if it's a recurring source of syntax mistakes for you, that you consider switching to 1D plaintext "Maple Notation" for input.

Upvotes: 1

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