for loops and storing values

Question

hussain askar 2021-10-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1573358-for-loops-and-storing-values

编辑： Stephen23 2021-10-28

I'm adding a constraint to my problem, the two constraints are the ones inside c. I want my c output to be 46 x 4 = 184 values. However, when i run my code, as the two “for loops” are completed, the value of “c” is replaced. In other words, the old value of “c” is forgotten when the loop takes different values of “i” and “h” and only the last value of “c” for h=23 and i=4 are returned to the main routine. what can i do to solve this?

for h= 1:23

for i =1:4

c = [-DR(i)-p(h+1,i)+p(h,i);p(h+1,i)-p(h,i)-UR(i)];

end

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Answer 1

Stephen23 2021-10-28

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1573358-for-loops-and-storing-values#answer_818363

编辑：Stephen23 2021-10-28

在 MATLAB Online 中打开

"what can i do to solve this?"

Use indexing into a preallocated array:

c = nan(46,4); % <--- preallocate!
for h = 1:23
    for i = 1:4
        c(2*h-[1,0],i) = [-DR(i)-p(h+1,i)+p(h,i);p(h+1,i)-p(h,i)-UR(i)];                
    end % ^^^^^^^^^^^ indexing!
end