Qiming
Posts:
10
Registered:
12/21/12


Re: get coefficients from a symbolic polynomial
Posted:
Jan 5, 2013 4:49 PM


"Nasser M. Abbasi" wrote in message <kca2be$9dd$2@speranza.aioe.org>... > On 1/5/2013 9:49 AM, Qiming wrote: > > > > > Note that the entire polynomial is symbolic, that is, even the coefficients 0, 1, 2, 3 > >are in symbolic form instead of numbers, so I cannot use 'sym2poly(y)' to get the coefficients. > > Can you show why you can't? i.e. show what you tried, and the error you get, as it works for me: > > EDU>> syms x > EDU>> y=3*x^3 + 2*x^2 + x; > EDU>> sym2poly(y) > > ans = > > 3 2 1 0 > > > Nasser
Hi Nasser:
Thanks for your reply.
In your case, actually only 'x' is symbolic, the coefficients 0,1,2,3 are already in numerical form. But my question is: what if 0,1,2,3 are all in symbolic forms?
I only give a simple example so that you might think why can't I directly put 0,1,2,3 in the expression. However, in my real application, those coefficients long and complicated and are generated by MATLAB symbolic tool box. I just want to "retrieve" those coefficients for my future use. Of course I can check those coefficients from the command window, but I don't want to put them back in my code by hand.
Qiming

