I've managed to use ployfit(X,Y,1) to get the two readings but I'm unsure on how to add the line and caption to the actual plot.
Any help?
MATLAB: Struggling to add the polynomial line
polyfitpolyfitline
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Try this:
x = linspace(-2, 2, 500);y = x .^ 2 + 2;plot(x, y, 'b-', 'LineWidth', 2);grid on;fontSize = 20;xlabel('X', 'FontSize', fontSize);ylabel('Y', 'FontSize', fontSize);ylim([0, 7]);% Pick a point at -1 (or wherever) and plot the tangent
xTangent = -1;% Equation of the tangent is y = slope*x + offset
% From the equation y=x^2 we know the slope is 2*x.
% Find the slope at x = xTangent.
slope = 2 * xTangent;% We want to plot the tangent line where it just touches the curve,
% so we need to know the y value at xTangent.
yTangent = xTangent .^ 2 + 2; % Y value of curve at x = xTangent.
hold on;plot(xTangent, yTangent, 'r*', 'LineWidth', 2, 'MarkerSize', 10);% Use point slope formula of a line to get equation for y
% y-y0 = slope*(x-x0).
% y = slope * (x - xTangent) + yOffset
yTangentLine = slope * (x - xTangent) + yTangent;plot(x, yTangentLine, 'b-', 'LineWidth', 2);
Read about polyfit. If (x,y) are your data points.
p = polyfit(x,y,1) ; yi = polyval(p,x) ;scatter(x,y);hold onplot(x,yi,'r')
Best Answer