MATLAB Answers

RAJ
1

array manipulation in loop through a sequence

Asked by RAJ
on 2 Sep 2019
Latest activity Commented on by RAJ
on 5 Sep 2019
Dear programmers
I have defined an array of 4 values with 1 in all the rows initially as : tissue = [1 1 1 1]
After 1st iteration, I want to replace '1' at 4th position by '2' as: [1 1 1 2].
After 2nd iteration, '2' wil be shifted to 3rd position and new value '3' will take the 4th position as: [1 1 2 3 ] .
After 3rd iteration, '2' wil be shifted to 2nd position ,'3' wil be shifted to 3rd position and new value '4' will take the 4th position as: [1 2 3 4].
After 4th iteration, '2' wil be shifted to 1st position ,'3' wil be shifted to 2nd position, '4' wil be shifted to 3rd position and new value '5' will take the 4th position as: [2 3 4 5].
In the below code even if I am being asked the iteration number but I am getting the results only for the i=4. Where am I doing the error ? Please help!
E = zeros(1,4);
for i=1:4
E(i) = 1
end
prompt = 'What is the iteration number? ';
i = input(prompt)
for i=1:4
E(5-i)= 2
for i=2:4
E(6-i)= 3
for i=3:4
E(7-i)= 4
for i=4
E(4)=5
end
end
end
end

  1 Comment

i = input(prompt)
assigns a particular value to i according to the user's input
for i=1:4
then overwrites i with the value 1, then 2, then 3, then 4.

Sign in to comment.

1 Answer

Answer by Andrei Bobrov
on 2 Sep 2019
 Accepted Answer

E = ones(4);
n = size(E,1);
for ii = 1:n
E(ii,n-ii+1:n) = E(ii - 1 + (ii == 1),n-ii+1:n) + 1
end

  3 Comments

Dear Mr. Andrei
Thank you for your help.
I found your way quite fascinating and it is working as well. But in my problem I want to take E just as a single column array where the values will be pushed up from 4th position to 1st position replacing the initialised value of 1 at all the four positions depending upon the iteration number which will be further dictated by ANSYS.
ANSYS will provide me the value of E4 after 1st iteration and again it will provide me with the new E4 value after 2nd iteration and consequenty E4 of the 1st iteration will be shifted to E3 and so on till iteration number 4.
So as everytime E4 will take a value as dictated from ANSYS and thus after that pushing of values will take place, Can you please throw a light in such a condition what can be done ?
E = ones(1,4);
A = zeros(4);
for ii = 1:4
E(end - ii + 1 : end) = E(end - ii + 1 : end) + 1
A(ii,:) = E;
end
Thanks Mr. Andrei your kind help and sorry for bothering you again .
It is almost done. But in the problem if the values are not incremented by 1 as in this case 2,3,4 and 5 but rather the values are random say 20,300.5,60 and 1.5. In that case the code is not working because in actual problem that I am working on, the values of E at 4th position can be anything and those will be read from a text file(in which the first column will be for an element and 2nd column is the E value that will take the position of E4 everytime and replace the previously positioned E4 to E3 i.e push one position ahead).
N.B: I am attaching the text file herewith. In the text file the 1st column is the finite element number and the 2nd column corresponds to the respective E that will take the place of E4. Such text files will be read in every iteration of the main program. I have tried to make a separate function by do loop to retrieve those E values row wise but that is not working.

Sign in to comment.