Finding slope and y intercept
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Hello, I was wondering if there is an easy way to find the slope and intercept of a line using MATLAB, like how it is so easy with Excel where you just plot the data and add a trendline, so then it will tell you the slope and intercept. Here is my code
tau = [15, 38, 100, 300, 1200];
CA = [1.5 1.25 1 0.75 0.5];
CA0 = 2;
dCdt = log((CA-CA0)./tau);
plot(log(CA),log((CA-CA0)./tau))
xlabel('ln(C_{A})')
ylabel('ln(C_{A}-C_{A0}/ \tau)')
I have a theory that says ln((CA-CA0)/tau) = ln(k) + alpha(ln(CA)), and I want to find alpha and ln k, which is my slope and intercept, respectively.
Thank you
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Accepted Answer
Sean de Wolski
on 20 Oct 2014
Have you tried the Curve Fitting App (Curve Fitting Toolbox, req'd)
>>cftool
3 Comments
Andrew Reibold
on 20 Oct 2014
If you just use polyfit to get linear data, just take two points from it and do the elementary calculations.
Sean de Wolski
on 20 Oct 2014
Student Version usually does come with CFT. Try calling:
>>cftool
To see if you do.
Then you can fit arbitrary functions and you don't have to worry about linearizing them to play with polyfit.
More Answers (2)
Torsten
on 17 Aug 2016
Did you look at the x-value where your "intercept" is between 0.32 and 0.33 ?
Best wishes
Torsten.
3 Comments
Torsten
on 17 Aug 2016
The p2-value always refers to x=0.
Thus to get the computed value of 0.3046, you must look at the intercept at x=0, not at x=3.85.
Best wishes
Torsten.
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