How to use sum series in Matlab
조회 수: 29 (최근 30일)
이전 댓글 표시
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.
댓글 수: 1
Stephen23
2015년 4월 11일
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.
채택된 답변
Jonathan Campelli
2015년 4월 10일
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
댓글 수: 3
Jonathan Campelli
2015년 4월 13일
I apologize for the mistake, and I'm glad you found it even though I was away.
추가 답변 (3개)
Image Analyst
2015년 4월 10일
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)
댓글 수: 2
Image Analyst
2015년 4월 10일
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
2015년 4월 10일
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
댓글 수: 0
Atinesh S
2015년 4월 10일
댓글 수: 4
Jonathan Campelli
2015년 4월 10일
I am unable to call X(i) using symsum. If you are able, Image Analyst has provided vectorized computations that are a lot cleaner.
참고 항목
카테고리
Help Center 및 File Exchange에서 Logical에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!