MATLAB: Finding the derivative of a graph

derivative

I have a 60×1 vector which i plotted against time (60 units). I want to determine the derivative of that graph. How do i do that

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Example

t=0:0.1:10
y=t.^2
dy=gradient(y,t)
subplot(211);
plot(t,y)
subplot(212)
plot(t,dy)

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MATLAB: How to draw tangent line at infleciton point

You have the slope at the inflection point as well as the ‘t’ and ‘y’ values at the inflection point, so all you need to do to draw the tangent line at the inflection point is to calculate the slope ‘b’, and that is straightforward.

I would use the gradient function to calculate the derivative, not diff, and the del2 function to calculate the second derivative, both because they are more accurate and because the result of each vector is the same length as the input vector.

MATLAB: How to plot a tangent line of specific point (x,y) of function y=x^2+2

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);

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Related Solutions

MATLAB: How to draw tangent line at infleciton point

MATLAB: How to plot a tangent line of specific point (x,y) of function y=x^2+2

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