# How can I create a best fit polynomial for my data?

3 visualizaciones (últimos 30 días)
Syed Ali Zaryab el 4 de Sept. de 2018
Comentada: Titus Edelhofer el 9 de Sept. de 2018
I have a set of data points that I received from a supplier which gives relative efficiency based on values of x and y. I want to create a polynomial similar to the one given below using the data provided Efficiency = a * (x)^2 + b * (x*y) + c * (y)^2 + d * (x)+ e * (y) + f
So basically what I want is a function which optimizes the value of a,b,c,d,e and f for me and gives me results that are almost similar to the one in the data table.
Attached herewith is the picture of the graph that the supplier provided along with the data points. Can you please tell me what functions can I use in Matlab to help me achieve this task.
##### 0 comentariosMostrar -2 comentarios más antiguosOcultar -2 comentarios más antiguos

Iniciar sesión para comentar.

Titus Edelhofer el 4 de Sept. de 2018
Hi Syed,
if I assume you have three (column) vectors x, y and Efficiency, then it's simply a linear regression problem:
A = [x.^2 x.*y y.^2 x y ones(size(x))];
sol = A \ Efficiency;
Then sol contains the (best approximation) values a,...,f.
Titus
##### 3 comentariosMostrar 1 comentario más antiguoOcultar 1 comentario más antiguo
Torsten el 7 de Sept. de 2018
Use "reshape" to change x, eff and y from (4x13) matrices to (52x1) vectors.
Titus Edelhofer el 9 de Sept. de 2018
Or use (:), i.e.,
x = x(:);
y = y(:);
eff = eff(:);
Titus

Iniciar sesión para comentar.

### Categorías

Más información sobre Get Started with Curve Fitting Toolbox en Help Center y File Exchange.

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by