how to do curve fiting of polynom?

q_vec=-0.0141600000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.00943999999999996	-0.00944000000000003	-0.00944000000000003	-0.00707999999999998	-0.00707999999999998	-0.00472000000000001
s_veq=0.700000000000000	0.909545454545454	1.11909090909091	1.32863636363636	1.53818181818182	1.74772727272727	1.95727272727273	2.16681818181818	2.37636363636364	2.58590909090909	2.79545454545455	3.00500000000000
plot(s_veq,q_vec)

[Luna]

Hi Elina,

Please first explain your question clearly and what do you want to do.

Also please correct your syntax error on that code part you have shared.

Answer 1

[Star Strider]

Try this:

q_vec = [-0.0141600000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.00943999999999996	-0.00944000000000003	-0.00944000000000003	-0.00707999999999998	-0.00707999999999998	-0.00472000000000001];
s_veq = [0.700000000000000	0.909545454545454	1.11909090909091	1.32863636363636	1.53818181818182	1.74772727272727	1.95727272727273	2.16681818181818	2.37636363636364	2.58590909090909	2.79545454545455	3.00500000000000];
plot(s_veq,q_vec)

How are ‘S’ and ‘Q’ related to ‘s_veq’ and ‘q_vec’?

EDIT —

With respect to fitting them, it depends on what you want to do.

Two examples:

q_vec = [-0.0141600000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.00943999999999996	-0.00944000000000003	-0.00944000000000003	-0.00707999999999998	-0.00707999999999998	-0.00472000000000001];
s_veq = [0.700000000000000	0.909545454545454	1.11909090909091	1.32863636363636	1.53818181818182	1.74772727272727	1.95727272727273	2.16681818181818	2.37636363636364	2.58590909090909	2.79545454545455	3.00500000000000];

p1 = polyfit(s_veq,q_vec,1);
v1 = polyval(p1, s_veq);

p5 = polyfit(s_veq,q_vec,5);
v5 = polyval(p5, s_veq);

figure
plot(s_veq,q_vec, 'pg', 'MarkerFaceColor','g')
hold on
plot(s_veq, v1, '-b')
plot(s_veq, v5, '-r')
hold off
grid
legend('Data', '1^{st}-Order Polynomial', '5^{th}-Order Polynomial', 'Location', 'NW')

Answer 2

[Luna]

As far as I understand from your question I have fixed your array definition as follows:

Please read my comments below. And check this link for more info: Polynomial Curve Fitting

q_vec= [-0.0141600000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.0118000000000000	-0.00943999999999996	-0.00944000000000003	-0.00944000000000003	-0.00707999999999998	-0.00707999999999998	-0.00472000000000001];
s_veq=[0.700000000000000	0.909545454545454	1.11909090909091	1.32863636363636	1.53818181818182	1.74772727272727	1.95727272727273	2.16681818181818	2.37636363636364	2.58590909090909	2.79545454545455	3.00500000000000];

%% Fitting part
p = polyfit(s_veq,q_vec,2); % gets the coeffs of fitted polynomial, I used 2nd degree you can change it by yourself as you wish.
f = polyval(p,s_veq); % creates the new y axis values from that polynomial. 
plot(s_veq,q_vec,'*r',s_veq,f,'-b'); % plots red stars the existing data and blue line for fitted data.

% your polynomial coefficients are in the array p with P(X) = P(1)*X^N + P(2)*X^(N-1) +...+ P(N)*X + P(N+1) descending order.
% your polynomial results are in the array f which gives Y = P(X).