a) Write a function to fit data to a line of the form y = ax + b. Use the follow

Question

a) Write a function to fit data to a line of the form y = ax + b. Use the following equations to obtain the line properties (the function name is myline): a = (sigma x_i)(sigma y_i) - n sigma x_iy_i)/(sigma x_i)^2 -n (sigma x_i^2) b = (sigma x_i)(sigma x_iy_i) - (sigma x_i^2)(sigma y_i)/(sigma x_i)^2 -n (sigma x_i^2) b) Use these four data points (1, 1), (2, 2), (4, 2), (5, 3) to test your function. c) Verify your function by comparing your result with the one obtained by Matlab function polyfit.

Explanation / Answer

Matlab function:

function [a,b] = myline(x,y)
n = size(x,2);
a = (sum(x)*sum(y) - n*(sum(x.*y)) ) /( (sum(x))^2 - n*sum(x.*x) );
b = ( sum(x)*(sum(x.*y)) - (sum(x.*x))*sum(y) ) / ((sum(x))^2 - n*sum(x.*x));
end

Sample Output:

x = [1,2,4,5];
y = [1,2,2,3];
p = polyfit(x,y,1)

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