Hi all !

I have a list of coupled ordinary differential equations 

L := [e1,e2,e3] = [diff(z(t), t, t)*m = 0, diff(x(t), t, t)*m - B*diff(y(t), t)*q = 0, diff(y(t), t, t)*m + B*diff(x(t), t)*q = 0] with unknown functions x(t),y(t),z(t).

I want to obtain the list of "normal forms" of the ode using the DEnormal function. The help page says that it is possible to use it with an operator list but none example is given. 

Thanks!

Kevin

Dear all, 

I am trying to use the Physics package to perform a simple computation about the expression of speed and acceleration in the local polar basis (Frenet). I am trying to get something like :

Define the position vector :

differentiate wrt t to get the velocity vector 

simplifying 

Similarly :

simplifying

Can anyone please help me ? Many thanks!

Hi ! 

I want to know how to ask Maple to transform a system of ODE in cartesian coordinates (e.g. [x'(t)=u(t) , u'(t)=-x(t)])

into a system in polar coordinates (in my example [r'(t)=0, theta'(t)=-1]). 

Many thanks!

Kevin