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I have the following data: ET = [1 3 5 7 6 4], and below is my code:
for i=1:3
meanET(i)=ET(:,1+(2*i-2)); %//for i=1,extract ET column 1 data
stdET(i)=ET(:,2+(2*i-2));
totalET(i)=meanET(i)+stdET(i)
end
However, MATLAB display's an error that says that in the assignment A(I)=B, the number of elements in B and I must be the same, and therefore I modified my code to this:
for i=1:3
meanET=ET(:,1+(2*i-2));%for i=1,extract ET column 1 data
stdET=ET(:,2+(2*i-2));
totalET=meanET+stdET
end
After running the latter code, it showed meanET=6, stdET=4, and totalET=10, which means that it only stored the data for i=3 in the workspace. I want to get the result like
totalET=[4 12 10] in the workspace, corresponding to i = 1, 2, 3. How do I do that?
OR you could just go with a simple vectorized solution:
>> totalET = ET(1:2:5) + ET(2:2:6)
totalET =
4 12 10
you should just declare your target array at the beginning of your code:
meanET=zeros(size(ET,1),3);
stdET=zeros(size(ET,1),3);
for i=1:3
meanET(:,i)=ET(:,1+(2*i-2));
stdET(:,i)=ET(:,2+(2*i-2));
end
totalET=meanET+stdET
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In a sample code I have X(1:n, 1)
I don't understand how it works
n=3 in a sample
Is it a matrix? but isn't () used for indexing so how it's a double index?
I imagine that your X is a two-dimmensional matrix. Generalizing, it can be said that to access the elements of a matrix is done with: X(n,m).
The common case is to get one single number, in that case n and m are integer numbers. But you can also pass vectors to n and m positions and that way extract a submatrix from the original one.
As an example:
X = [1 2 3; 4 5 6; 7 8 9]
X(1:3,1) = [1; 4; 7]
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I understand how the program works but I have a little bit of confusion. If anybody can explain, that will be great. The output is 21, 12. Does it work like 7*3=21 and 4*3=12?
mat=[7 11 3; 3:5];
[r,c]=size(mat);
for i=1:r
fprintf ('The sum is %d\n',sum(mat(i,:)))
end
mat(i,:) will give you all values in the first row of mat. In your example, this first row is [7 11 3], and the second row is [3 4 5]. The outputs you're seeing are the sums of all values in each row (7+11+3=21).
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I have a question please if we have structure with 3 dimension and each field of them has 7 values how can extract each value from each field of this structure separately.
Just use indexing:
>> s(1,1,1).data = [1 2 3 4];
>> s(1,1,2).data = [10 20 30 40 50]; %// example struct
>> s(1,1,2).data(3)
ans =
30
>> s(1,1,2).data(2:4)
ans =
20 30 40
Also, it's better not to use struct as a variable name, because struct is a built-in function.
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I want to generate an array of random numbers that are divisible by 3 in matlab. What is the way to do this?
try this:
a = randi(100, 5) * 3;
a = a(:);
use randi(100, 5) to create a pseudo random 5x5 matrix of integers between 1 and 100. multiply by 3 to make them all divisible by 3. use the colon operator : to convert it to a 25 long array.
As suggested by #tashuhka you can avoid the : by:
a = randi(100, [25,1]) * 3;
You can read all about it here
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I need to do an optimization problem using ga algorithm. The number of decision variable is 3. i.e 3 x 1 matrix. but first element is always 0. keeping this as reference I want to optmize other two variables. How can I do this task?
Then just use
lb = [0,0,0];
ub = [0,8,8];
IntCon = [0 2 3];