Question

I am not experienced in using Maple or Matlab’s mupad and I want to do the next:

parametric:={x=a3*t^3+a2*t^2+a1*t+a0, y=b3*t^3+b2*t^2+b1*t+b0}

inplicit:= 0=uxxx*x^3+uxxy*x^2*y+uxyy*x*y^2+uyyy*y^3+uxx*x^2+uxy*x*y+uyy*y^2+ux*x+uy*y+u0;

Having this two equations I want to find the analytical expression written as:

v9*t^9+v8*t^8+...+v1*t+v0=0;

I tried with the command simplify(subs(implicit,parametric)) but the result it gives me is just the next one.

0 = u0 + uxx*(a3*t^3 + a2*t^2 + a1*t + a0)^2 + uxxx*(a3*t^3 + a2*t^2 + a1*t + a0)^3 + uyy*(b3*t^3 + b2*t^2 + b1*t + b0)^2 + uyyy*(b3*t^3 + b2*t^2 + b1*t + b0)^3 + ux*(a3*t^3 + a2*t^2 + a1*t + a0) + uy*(b3*t^3 + b2*t^2 + b1*t + b0) + uxy*(a3*t^3 + a2*t^2 + a1*t + a0)*(b3*t^3 + b2*t^2 + b1*t + b0) + uxxy*(a3*t^3 + a2*t^2 + a1*t + a0)^2*(b3*t^3 + b2*t^2 + b1*t + b0) + uxyy*(a3*t^3 + a2*t^2 + a1*t + a0)*(b3*t^3 + b2*t^2 + b1*t + b0)^2

Don’t read it, it is just the x equation written in place of x, but without any more equation development. I just can’t find the way of writting the equation in the way I want.

Any help will be very appreciated!

Answer 1

It seems you need to use ‘collect’ command instead ‘simplify’.

Try following command:

collect(subs(implicit,parametric),t)

Reference for MATLAB documentation on command:
http://www.mathworks.com/help/symbolic/collect.html