MaplePrimes - answers and comments on Question, Differentiating Vector Functions?

Elementwise operations

alsholm — Wed, 17 Mar 2010 15:58:02 Z

Say your vector is

v:= <a(t),b(t),c(t)>;

then in Maple 13 you can differentiate elementwise like this

diff~(v. t):

where you should notice the tilde.

In earlier versions:

map(diff, v, t);

map is still useful, though.

Preben Alsholm

Crash..

MrAdam — Wed, 17 Mar 2010 16:55:10 Z

So.. i don't know if im doing something wrong here... but maple crashes when running the last part of this document: https://docs.google.com/fileview?id=0Bx5y79IuSOVJNWYzMTE0MTgtOTQxOS00YzFhLThiZDItMzdhMThlYWIyZWM1&hl=en

You may also check out the

Thomas Unger — Wed, 17 Mar 2010 16:56:23 Z

You may also check out the VectorCalculus package. It contains -among other vector operation goodies- a diff command that natively maps diff to a vector.

solve

Robert Israel — Wed, 17 Mar 2010 22:18:04 Z

It doesn't crash for me, it just doesn't return a value. The main problem here is that If R and V are Vectors, R . V will use the complex conjugate of R. In your case this shouldn't make a difference, because you want t > 2, but Maple doesn't know that when it computes r(t) . v(t). One way to avoid that is to use the transpose of the first vector, so that "." will be just ordinary vector multiplication: thus r(t)^%T . v(t).

> solve({r(t)^%T . v(t), t > 2, t <= 27}, t);

{t = 13.58622459}, {t = 17.71237270}