I want to define a vector function, then plot it, differentiate it, etc.
The best I've been able to do so far is to define it two different ways: one for evaluating, one for symbolic manipulation
r:= < cos(t), sin(t), t >; # symbolic version of function, for example to take derivative
# returns derivative,
rf := (t)->evalf( < cos(t), sin(t), t > ); # returns numerical value of function
# we use numerical version to plot
rCurve := spacecurve( rf(t), t = -1 .. 1 );
# But how to return value of derivative?? Next line doesn't work.
df := (t)->evalf( diff(r,t) );
But how do I plot the derivative? The last line doesn't work. I've tried various variations but no luck.
I don't think this approach is write (why define two different ways?) but haven't been able to figure out how to do it.
Various online docs haven't helped.