how to create a series of changes over the loop variable and can assign a value to it

Question

Pham Ngoc Thanh 2013-5-18

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how to create a series of changes over the loop variable and can assign a value to it Example

for r=1:3
  A|r| = r 
  B|r| = A|r+1| + A|r|
end
the result
A1=1
A2=2
A3=3
B1=3
B2=5
...

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Answer 1

Youssef Khmou 2013-5-19

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try :

 n=1:30;
 A=n;
 for r=1:length(n)-1
   B(r)=A(r+1)+A(r);
 end

plot(A), hold on, plot(B)

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Youssef Khmou 2013-5-19

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hi, In this case, the dimension grows inside the loop so you need to use the cell :

 for i=1:4
  A{i}=rand(3,4+i);
 end

Pham Ngoc Thanh 2013-5-19

Hi I have tried

for i=1:4

A{i}=rand(3,4+i);

end but have an error: "Cell contents assignment to a non-cell array object" What can I do?

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Answer 2

Image Analyst 2013-5-19

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You don't have a good condition for when r = the last value, for example, what is A(4) when r only goes to 3. But ignoring that last element, this will work for you:

n=10
A=1:n
B = A + [A(2:end) 0]

In command window:

n =
    10
A =
     1     2     3     4     5     6     7     8     9    10
B =
     3     5     7     9    11    13    15    17    19    10

If you want to add the last element of A then turn the 0 into A(n).

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Answer 3

Image Analyst 2013-5-19

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This works just fine (if that's what you want to do):

clc;
for i=1:4
  A{i} = rand(3,4+i)
end
whos A
A = 
    [3x5 double]
A = 
    [3x5 double]    [3x6 double]
A = 
    [3x5 double]    [3x6 double]    [3x7 double]
A = 
    [3x5 double]    [3x6 double]    [3x7 double]    [3x8 double]
  Name      Size            Bytes  Class    Attributes
    A         1x4              1072  cell