MATLAB: How can I plot y = e^(-2x)Sin2x and its derivative on the same graph using two different colors

derivativesplots

I'm learning Matlab for the first time and I was able to get the first graph working but i'm having trouble getting the graph of the derivative to work. I keep getting an error message that "vectors must be the same lengths" and that i have an error in line 9.
x = (0:0.02:5);
y= exp(-2*x).*sin(2*x);
subplot(1,2,1)
plot(x,y),xlabel('x'),ylabel('y'), axis([0 5 -1 1])
hold on
diff(y) %differentiation
f = diff(y);
plot(x,f,'r'),xlabel('x'),ylabel('f'), axis([0 5 -1 1]) <-------line 9

Best Answer

The easiest solution is to use the gradient function rather than diff. The gradient function produces a more accurate estimate and the output is the same length as the input, while the output of diff is one element shorter, owing to the different ways the two are calculated.
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