Create number of for loops depending on size of N

Question

Victor 2024-5-26

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2122741-create-number-of-for-loops-depending-on-size-of-n

评论： Victor 2024-5-27

采纳的回答： Image Analyst

Hi, i have a question regarding number of nested loops:

In this case N would be 4 and hence there are 4 for loops

But if N = 2 in need 2 for loops and the formula also changes to i_1+1_2/N where N=2

is it possible to create code that creates the correct amount of for loops (corresponding to the value of N)

and also changes the formula for i_value in a correct way.

i_Max = 8

i_value = [];

i_real = [];

i_first = [];

i_second = [];

i_third = [];

i_forth = [];

tol = 0.01;

i_good = false;

while i_good == false

% generate new ratio's

for i_1 = 1:0.1:i_Max

for i_2 = 1:0.1:i_Max

for i_3 = 1:0.1:i_Max

for i_4 = 1:0.1:i_Max

i_value(end+1) = (i_1+i_2+i_3+i_4)/N;

if (i_average-tol <i_value(end)) && (i_value(end)<i_average+tol)...

&& (i_1>i_2) && (i_2>i_3) && (i_3>i_4)

i_good =true;

i_real(end+1) = i_value(end);

i_first(end+1) = i_1;

i_second(end+1) = i_2;

i_third(end+1) = i_3;

i_forth(end+1) = i_4;

end

4 个评论
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Torsten 2024-5-26

编辑：Torsten 2024-5-26

@Victor

I think you changed the loops in the meantime. That's not fair :-)

Victor 2024-5-27

Thank you Torsten for providing code for my problem!

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Answer 1

Image Analyst 2024-5-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2122741-create-number-of-for-loops-depending-on-size-of-n#answer_1463566

在 MATLAB Online 中打开

OK, a not-clever but brainless and verbose approach is to just make a set of "if" blocks

if N == 2
    % Code for N=2
elseif N == 3
    % Code for N=3
elseif N == 4
    % Code for N=4
end

Hopefully you have a small, known and limited number of possibilities for N, like 2, 3, or 4. If you have hundreds of possibilities then you should re-think your algorithm.

1 个评论
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Victor 2024-5-26

Thank you, yes N_max = 6 so then it would be possible. Again thank you for your time answering my question

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Answer 2

Torsten 2024-5-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2122741-create-number-of-for-loops-depending-on-size-of-n#answer_1463576

编辑：Torsten 2024-5-26

在 MATLAB Online 中打开

The N columns of the resulting C-matrix contain i_first, i_second,...

imax = 8;
N = 4;
i_average = (sum(0:N-1)/N+sum(imax:-1:imax-N+1)/N)/2;
tol = 0.5;
C = nchoosek(0:imax,N)
C = 126x4
     0     1     2     3
     0     1     2     4
     0     1     2     5
     0     1     2     6
     0     1     2     7
     0     1     2     8
     0     1     3     4
     0     1     3     5
     0     1     3     6
     0     1     3     7
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
C = sort(C,2,'descend')
C = 126x4
     3     2     1     0
     4     2     1     0
     5     2     1     0
     6     2     1     0
     7     2     1     0
     8     2     1     0
     4     3     1     0
     5     3     1     0
     6     3     1     0
     7     3     1     0
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
i_value = sum(C,2)/N
i_value = 126x1
    1.5000
    1.7500
    2.0000
    2.2500
    2.5000
    2.7500
    2.0000
    2.2500
    2.5000
    2.7500
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
idx = abs(i_value-i_average)<tol
idx = 126x1 logical array
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   1
   1
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   1
   1
   1
   1
   0
   0
   0
   1
   0
   1
   1
   1
   1
   0
   1
   1
   1
   1
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   1
   0
   1
   1
   1
   1
   0
   0
   0
   1
   1
   1
   1
   1
   1
   0
   0
   1
   1
   0
   0
   0
   0
   0
   0
   0
   0
   0
   1
   1
   1
   1
   1
   0
   0
   0
   0
   1
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
   0
C = C(idx,:)
C = 34x4
     8     6     1     0
     8     7     1     0
     8     5     2     0
     7     6     2     0
     8     6     2     0
     8     7     2     0
     8     4     3     0
     7     5     3     0
     8     5     3     0
     7     6     3     0
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>