How to find derivative of CSV data plot?
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jasper kansiime
on 28 Sep 2018
Commented: Star Strider
on 30 Sep 2018
I have a csv file with uniform points but i would like to write MATLAB code for obtain the derivative of the plotted function(unknown) with time. How can i do this?
if true
% code
end
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Accepted Answer
Star Strider
on 28 Sep 2018
[D,S,R] = xlsread('Uniform_points.csv');
t = D(:,1);
f = D(:,2);
dt = mean(diff(t));
df = gradient(f,dt);
figure
subplot(2,1,1)
plot(t, f)
grid
title(S{2},'Interpreter','none')
xlabel(S{1})
subplot(2,1,2)
plot(t, df)
grid
title(['d(',S{2},')/dt'],'Interpreter','none')
xlabel(S{1})
6 Comments
Star Strider
on 30 Sep 2018
To simply alter the plot x-tick labels, this works:
t_new = 0:0.04:0.4;
figure
plot(t, f)
xt = get(gca, 'XTick');
xtv = linspace(min(xt), max(xt), numel(t_new));
set(gca, 'XTick', xtv, 'XTickLabel',t_new)
I generalised it, so it is a bit more complicated than it needs to be for the current values. It will work for other ‘t_new’ vectors without further modification.
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