r(t):= <t | t^(2) | (t^(2) )/(2) >

simplify(,symbolic)

diff(r(t),t)

The three lines above are part of a worksheet that computes unit tangent vector, unit normal vector and components of acceleration for a parametric curve r(t) ,  a standard Calc 3 lesson.

I am...

 rtoc(x,y,z):= < sqrt(x^(2)+y^(2)) | if 0<x then (arctan(y/(x)))else (Pi+arctan((y)/(x)) )end if  ; | z     >

I am a new user migrating my calculus labs from Derive to Maple.

One exercise asks the student to "write a program" to convert coordinates of a point between 3-D coordinate systems. 

I have tried the function definition given above and the error message is "unable...