How to use sum series in Matlab
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I need to use sum series in some assignments. But don't know the syntax
I'm just trying to write sum series as below
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/148945/image.png)
Code
k = sum(i^2, i = 1..4)
But I'm getting this error message
The expression to the left of the equals sign is not a valid target for an assignment.
1 件のコメント
Stephen23
2015 年 4 月 11 日
The documentation for MATLAB is really rather good, and includes lots of complete, working examples:
You should look at it one day. Looking at the documentation would immediately give a much better idea of how to use the function max than just inventing some syntax. After all, the people who wrote that function are probably the best ones to describe how it can be used.
採用された回答
Jonathan Campelli
2015 年 4 月 10 日
I'm providing another solution to address the longer summation you have posted in my first answer. Please let me know if this suits your needs:
data = load('ex1data1.txt');
y = data(:, 2);
m = length(y);
X = [ones(m, 1), data(:,1)];
theta = zeros(2,1);
i=1:m;
J=sum(((theta(1)+theta(2).*X(i,2))-y(i)).^2)
Best,
Jonathan
3 件のコメント
Jonathan Campelli
2015 年 4 月 13 日
I apologize for the mistake, and I'm glad you found it even though I was away.
その他の回答 (3 件)
Image Analyst
2015 年 4 月 10 日
If you want to use a for loop, try this:
theSum = 0;
for i = 1 : 4
theSum = theSum + i ^ 2;
end
Or if you want a vectorized solution, try this:
i = 1 : 4;
theSum = sum(i .^ 2)
2 件のコメント
Image Analyst
2015 年 4 月 10 日
OK, but that looks totally different than your original post where you mentioned nothing about y, m, X, J, data, or theta. All you mentioned was "i" and the sum that you called "k".
I don't have any symbolic toolboxes. Is that a requirement that you do it that way rather than the simple numerical way?
Jonathan Campelli
2015 年 4 月 10 日
Hello Atinesh
syms i %Creat symbolic variable 'i'
symsum(i^2, i, 1, 4) %Use symsum to run your summation operation
Best regards,
Jonathan Campelli
0 件のコメント
Atinesh S
2015 年 4 月 10 日
4 件のコメント
Jonathan Campelli
2015 年 4 月 10 日
I am unable to call X(i) using symsum. If you are able, Image Analyst has provided vectorized computations that are a lot cleaner.
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