I have a 2 datasets of .mat files which contain 1*418 matrix in both the .mat files how to plot the regression line for that. I have plottedd the scatter plot for it after that i couldnot able to proceed.
can any one help me.
Thank you.
MATLAB: How to plot single row values of 2 .mat files with linear regression line through it
helplinear regressionlinear regression modellinearregressionregressionregression modelregression models
Related Solutions
Because the syntax should be
polyfit(x,y,N)
and not
polyfit(y,x,N)
Here is some code that illustrates the fix:
x = 1:503;
y = 250 + 0.02*x + 0.005*x.^2 + 0.2*rand(1,503).*x;
figure polyfit(y,x,0); coef1 = polyfit(x,y,0); y1 = polyval(coef1,x); hold on plot(x,y,'.'); plot(x,y1); polyfit(x,y,1); coef2 = polyfit(x,y,1); y2 = polyval(coef2,x); plot(x,y2); polyfit(y,x,2); coef3 = polyfit(x,y,2); y3 = polyval(coef3,x); plot(x,y3);
The inverse of a polynomial is not a polynomial, so you cannot simply interpolate the inverse function. Following shows two approaches
1) fzero()
x = linspace(0, 2, 8);y = 5*x.^6 + 3*x.^5; % y varies from 0 to 416.
pf = polyfit(x, y, 6);y_pred = @(x) polyval(pf, x);% find x, when y = 100;
y_val = 100;x_val = fzero(@(x) y_pred(x)-y_val, rand);2) Polynomial root finding. This method gives all possible solutions
x = linspace(0, 2, 8);y = 5*x.^6 + 3*x.^5; % y varies from 0 to 416.pf = polyfit(x, y, 6);% find x, when y = 100;y_val = 100;pf(end) = pf(end)-y_val;x_vals = roots(pf);x_vals = x_vals(imag(x_vals)==0); % if you only want real roots.
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