# How to obtain values symbolically

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Vicky on 22 Feb 2013
Hi! Im using Matlab version 7.9.0(R2009b) and i would like to sum e.g. first 10 terms of expression c_i*x^i, where c_i should be obtained symbolically. how should i do that, so that this expression is dependent on x / function of x (so when i enter exact number for x, i get real number - not expression with c_i).

Azzi Abdelmalek on 22 Feb 2013
Edited: Azzi Abdelmalek on 22 Feb 2013
EDIT
c=sym('c',[1 10])
x=sym('x')
f=@(x,n)sum(c(1:n).*x.^(1:n))
f(x,5)

Azzi Abdelmalek on 23 Feb 2013
Ity seems like a homework, I think you get enough help to finish the work.
Walter Roberson on 23 Feb 2013
If that is the complete instruction you are given, then the c_i are just the symbolic variables, and you will not be able to complete the second part.
If there are instructions before that point, then you might be able to proceed further.
Vicky on 23 Feb 2013
there should be sth else, but i cant find the answer...thank You, Walter, anyway.

bym on 23 Feb 2013
alternative:
c =sym(1:10)
f = @(x) sum(c.*x.^(1:length(c)));