Get fitting statistics from "solve"

Question

george hargenrader 2020-3-27

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编辑： Walter Roberson 2020-4-11

Question

1) How do I get the graphs to update nicely during the fitting precces.

2) How do I get statistics from the fitting precess?

Hello, I wrote a fitting script using the example here https://www.mathworks.com/help/optim/ug/fit-ode-problem-based-least-squares.html which was very helpful. The code is working fine, I just want to make it flashier, and report some statistics from the fit. Any advice would be appreciated.

I want to see each iteration of the fit, so I put plot commands in my function call RtoODE. However each time it plots, the first trace has lower y values than the next trace, meaning the y axis rescales each time. It's hard to see how the fit is changing when the y axis is constantly rescaling. Is there a better way to do this? Perhaps an option when calling "solve" that will show the iterations automatically?

I would also like to see the goodness of fit, such as the r^2. If I could get a plot of the goodness of fit for each iteration, showing the fit getting better and better, that would be wonderful. Is there a good way to do this?

I'm using MATLAB 2019a.

Thank you in advance!

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Answer 1

Jerome Blair 2020-3-28

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编辑：Walter Roberson 2020-4-11

You do all the plots once as follows:

p1 = plot(x1,y1,color1);
hold on
p2 = plot(x2,y2,color2);
etc.

Now set the y limits so they don't change:

ylim([ymin ymax])

Use values that will work for you.

Next is the code that changes all of the y arrays

Instead of plotting again you do

p1.YData = y1;
p2.YData = y2;

etc.

These changes to the YData field cause the plot to instantly change.

This sort of thing is covered in Chapter 17 of the MATLAB Graphics manual.

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george hargenrader 2020-4-10

using the

p1 = plot(x,y);

syntax works to some degree. But when y contains multiple lines then p1 will reference those lines. Any additional lines I add to the figure using hold on, are not referenced by p1.

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Answer 2

Jerome Blair 2020-4-11

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p1 can only reference 1 line. Additional lines must use p2, p3, etc., as in the example I sent. The different hanles, p1, p2, p3, etc., eg., can have any names you wish.

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george hargenrader 2020-4-11

p1 can reference multiple lines if they were plotted when p1 was initialized. For example the following can change the color.

p1 = plot(x,y); %Where y is a matrix, each row a line

p1(1).YData = new_y;

But when I use hold on to add more lines, p1 will not be able to access them.

So, while it's a neat idea, I don't think it helps me solve this particular problem.

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Answer 3

Jerome Blair 2020-4-11

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Of course p1 will not be able to access them. You have to acces them with p2 or p3--the handle that was used when theeh line was created--as in teh example I orginally sent.