How to use generated code from cftool to find unknown variables

Question

DARSHAN N KANNUR 2021-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/789844-how-to-use-generated-code-from-cftool-to-find-unknown-variables

回答： Walter Roberson 2021-4-5

I have three variables x y and z where x is speed (mx1 array), y is torque (nx1 array), z is efficiency (mxn array). This is a motor data. On using auto fit in cftool it chose interpolant-linear.

I want to find efficiency (z)of the motor at any given speed and torque (i.e x and y). I don't know what to do after generating the code and saving the results in workspace.

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Walter Roberson 2021-4-5

在 MATLAB Online 中打开

z_at_query = interp2(x, y, z.', x_query, y_query)

The .' on z is important. Your data has x going down columns, but in MATLAB x goes across rows.

DARSHAN N KANNUR 2021-4-5

Thank you so much. it worked. How to accept your answer.

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Answer 1

Steven Lord 2021-4-1

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https://ww2.mathworks.cn/matlabcentral/answers/789844-how-to-use-generated-code-from-cftool-to-find-unknown-variables#answer_664484

在 MATLAB Online 中打开

The fitted object you export to the workspace is an sfit object. You can evaluate an sfit object by passing the values at which you want to evaluate it into the object as shown in the example on that documentation page. The same holds for cfit objects:

load census

f = fit(cdate, pop, 'poly2')

f =

Linear model Poly2: f(x) = p1*x^2 + p2*x + p3 Coefficients (with 95% confidence bounds): p1 = 0.006541 (0.006124, 0.006958) p2 = -23.51 (-25.09, -21.93) p3 = 2.113e+04 (1.964e+04, 2.262e+04)

plot(cdate, pop, 'o-') % show the data

hold on

plot(1985, f(1985), 'x') % show the fitted value for 1985

The X looks to be pretty close to the line.

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DARSHAN N KANNUR 2021-4-5

could you please edit the code and send as per my requirement. where x, y, z variables are plotted using cftool with interpolant linear. where i should find z value for any x and y input.

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