MATLAB: Linear fit

plot

When plotting a scatter plot is it possible to add a linear fit to the the graph without having to go into tools-> basic fitting and clicking on linear and show equations?

Best Answer

lsline is in the Statistics Toolbox, if you do not have that product you can use polyfit() to fit a 1st order polynomial.

    x = 1:10; 
    y1 = x + randn(1,10); 
    scatter(x,y1,25,'b','*') 
    P = polyfit(x,y1,1);
    yfit = P(1)*x+P(2);
    hold on;
    plot(x,yfit,'r-.');

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The intercept is indeed 0.5. Intercept is the value on y-axis when x=0. Whereas you 2.2 is the value when x=1.

MATLAB: I dont know how to plot more than one regressions in one plot, like the picture i did in excel. I tried basic fitting tool but could not success, and i have look at multiple regression but could not understand becaus of no example. Thank for any he

Something like this should work:

x = 1:10;
y1 = rand(1, 10);
y2 = rand(1, 10);
DM = [x', ones(length(x),1)];                       % Design Matrix
B1 = DM \ y1';                                      % Estimate Parameters Of ‘y1’ Fit
B2 = DM \ y2';                                      % Estimate Parameters Of ‘y2’ Fit
y1_fit = DM*B1;                                     % Calculate Fit For ‘y1’
y2_fit = DM*B2;                                     % Calculate Fit For ‘y2’
figure(1)
plot(x, y1, '.b',  x, y2, '.r')                     % Plot Data
hold on
plot(x, y1_fit, '--b',  x, y2_fit, '--r')           % Plot Fitted Regression Lines
hold off
grid

Best Answer

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MATLAB: I dont know how to plot more than one regressions in one plot, like the picture i did in excel. I tried basic fitting tool but could not success, and i have look at multiple regression but could not understand becaus of no example. Thank for any he

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