Curve fitting??

I have 3 curves which are related to 2 variables. One dependent and another independent. I want relationship between these variables for all the three curves. Is this possible with curve fitting? I'm not sure. If yes could you please suggest an article closely related the above problem? I'm overwhelmed seeing the contents for curve fitting in general. If not curve fitting what else can help me in this matter? I also have a table with all the values. Can i use that instead of curves to form formula between variables?

Answer 1

[bym]

perhaps I am misunderstanding, but the following shows how to fit 3 curves in two variables:

clc;clear;close all
x = sort(rand(20,1));       % independent variable
X = [ones(20,1),x,x.^2];    % Vandermonde matrix

y = X*[1 2 3;2 2 3;3 3 5 ]; % dependant variable; arbitrary coefficients
y = y+rand(20,3)*.5;        % add noise

coeff = X\y;                % get coefficients
yhat = X*coeff;             % get predictions

plot(x,yhat);hold on;
plot(x,y,'.')               %plot

HTH