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Curve fitting using matlab 
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#1
Nov808, 11:18 PM

P: 3

1. The problem statement, all variables and given/known data
For the given set of data, find the leastsquare curve: A) f(x)=Ce^Ax, by using the change of variable X=x, Y=ln(y), and C=e^B to linearize the data points. B) f(x) = 1/(Ax+B), by using the change of variable X=x and Y = 1/y to linearize the data points. x : [ 1 0 1 2 3] y : [ 6.62 3.94 2.17 1.35 0.89] I need the matlab code on how to do these 2 problems im confused and which curve gives a better fit. ?? 2. Relevant equations This is the only code i know but idk how to do it with the question they are asking i need to pertain it to that function C = poly(X,Y,M) n=length(X); B=zeros(1:M+1); F=zeros(n,M+1); for k=1:M+1 F(:,k)=X'.^(k1); end A=F'*F; B=F'*Y'; C=A\B; C=flipud(C); 3. The attempt at a solution These are the coefficients: 0.0458x^3 0.5225x^2 2.1567x 3.9040 I am confused with what the question is asking i know im suppose to have a ans for part A and B 


#2
Nov1008, 12:29 AM

P: 18

Think about what a change of variable is, then figure out how to apply that to the data.
Aka, when you make a substitution for y=ln(y), that just means you take your y list, and just take the ln of that. That now because the new measurement for what used to be the yaxis. Does that make sense? 


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