For loop.how can I do it right?

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Amjad AL Hasan 2021-4-28

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评论： Amjad AL Hasan 2021-4-28

How can I do it right?

I am binger with MATLAB and I try to learn it. I have a data File with two columns ( x and y). The column x has content ages for the students and I should calculate the time between the ages using a "For" loop :

data=dlmread('volcanoes.dat')
x=data(:,2);
n=length(x);
for i=1:1:n
    t(i)=x(i+1)-x(i)
end
plot(x,t,'bo');

but there's something wrong with my loop. I don’t know how to write it. How can I do it right?

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Answer 1

Image Analyst 2021-4-28

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https://ww2.mathworks.cn/matlabcentral/answers/816270-for-loop-how-can-i-do-it-right#answer_687365

在 MATLAB Online 中打开

You can't go to n+1 when n is the last element of the vector. Try this:

data=dlmread('volcanoes.dat')
x=data(:,2);
n=length(x);
for i=1:n - 1
    t(i)=x(i+1)-x(i)
end
plot(x, t, 'bo');

or better yet.

data = dlmread('volcanoes.dat');
x = data(:, 2);
t = diff(x); % Subtracts each element from the next one in the list.
plot(x(1:end-1), t , 'bo-', 'LineWidth', 2, 'MarkerSize', 16);
grid on;
xlabel('x', 'FontSize', 20);
ylabel('t', 'FontSize', 20);