How to get this into a loop

2021 3 18
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更新时间：2021 3 18
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Hi there i like to ask how can i get this into a for loop
x=rand(1,20)
h1=(x(2,1)-x(1,1));%First interval
h2=(x(3,1)-x(2,1)); %second interval
h3=(x(4,1)-x(4,1));%Third interval
h4=(x(5,1)-x(4,1));
I like the interval to run for another 20 times
i get it as
for i=1:20
h=( x(1,n) -x(1,(n-1)
iter=iter+1
end
Through this method, i can get 20 iterations but the h is remain the same value, can i know why and how can i change it to get the right way

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Jan
Jan 2021-3-18
x = rand(1, 20)
h1 = x(2,1) - x(1,1); %First interval
This must fail: x has one row only, than x(2,1) does not exist. Please post some working code.

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David Hill
David Hill 2021-3-18

0 个投票

x=rand(1,20);
for k=1:19
h(k)=x(k+1)-x(k);
end
Or without loop
x=rand(1,20);
h=diff(x);

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Mark Loui
Mark Loui 2021-3-18
Hi thanks so much, i have another question
For example
x=rand(1,20);
for k=1:19
h(k)=x(k);
end
Can this be done?
As from what i seen it keeps getting the same output?
David Hill
David Hill 2021-3-18
You do not need a loop to set h=x
x=rand(1,20);
h=x;%h is an array

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更多回答（1 个）

Jan
Jan 2021-3-18
编辑：Jan 2021-3-18

0 个投票

Why do you want a loop? It is working without a loop also - guessing that you mean x(1, 2) and not x(2, 1) as in the code in the question:
x = rand(20, 20)
h1 = x(:, 2) - x(:, 1); % First interval
h2 = x(:, 3) - x(:, 2); % second interval
h3 = x(:, 4) - x(:, 4); % Third interval
h4 = x(:, 5) - x(:, 4);

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Mark Loui
Mark Loui 2021-3-18
编辑：Jan 2021-3-18
I like a loop the main question is y=rand(100,1)
I like to generate a for loop
for i=1:n-1
a(k)=y(k) %At each term i get one value extracted from the y
iter=iter+1
end
The extracted a(k) at different for each term is used later to find something else
Mark Loui
Mark Loui 2021-3-18
Hi there i got it already thanks.
But i have another question, i like to create a diag function with a loop where the matrix is depending on the nxn size, how can i do it ?
After creating the element i like to fill in each of the element with a value, i am having trouble with this matter and not able to get the right approach, please help
Jan
Jan 2021-3-18
What do you want your "diag function with a loop" to do? The explanation " matrix is depending on the nxn size" is not clear enough yet.

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