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HP Forum Archive 19

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Symbolic Calculus 50g
Message #1 Posted by Shu Y Pong on 28 Jan 2010, 8:40 p.m.

I am trying to figure out how to get the 50g to take the time derivatives symbolicly for r in dynamics problems. so r dot and r double dot as a function of theta. So the question is, is there a way to make the calculator see theta symbolicly as some unknown function of time instead of as a constant so that when it takes the derivative it executes the chain rule as it would if theta were a function instead of getting zero because it thinks theta is a constant. for instance if r = sin(theta) then r dot = cos(theta)*theta dot. instead the calculator just gives zero or if you take it with respect to theta then you just get cos(theta)

Edited: 28 Jan 2010, 8:43 p.m.

Re: Symbolic Calculus 50g
Message #2 Posted by Norman Dziedzic on 28 Jan 2010, 10:58 p.m.,
in response to message #1 by Shu Y Pong

You have to tell the calculator that theta is a function of t.

If you type in d/dt( cos ( theta(t) ) ) then you will get the result you expect. I get

cos( theta(t) ) * d1 theta(t)

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