Hello, is there any way I can define a matrix NxN whose elements are different real numbers between 0 and 5?

what about if I want to create a NxN matrix (1<N<2002) with random real number between 1 and 5 and the columns 1 and 2002 and the rows 1 and 2002 to be 0 ?

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Answer 2

Youssef Khmou 2013-10-13

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try :

N=300;
M=5*rand(N);

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jimaras 2013-10-13

thank you

jimaras 2013-10-13

what about if I want to create a NxN matrix (1<N<2002) with random real number between 1 and 5 and the columns 1 and 2002 and the rows 1 and 2002 to be 0 ?

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Answer 3

Azzi Abdelmalek 2013-10-13

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N=5
out=reshape(linspace(0,5,N*N),N,N)

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jimaras 2013-10-13

what about if I want to create a NxN matrix (1<N<2002) with random real number between 0 and 5 and the columns 1 and 2002 and the rows 1 and 2002 to be 0 ?

Azzi Abdelmalek 2013-10-13

编辑：Azzi Abdelmalek 2013-10-13

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M=rand(N)*5
M(randi(N*N))=0
M(randi(N*N))=5

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Answer 4

Image Analyst 2013-10-13

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In your comments, you specified both 0 and 1 as the lowest value, so I made it flexible enough to handle either one:

N = 10; % Whatever you want
lowestValue = 1; % or 0 - whichever you want.
highestValue = 5;
theMatrix = lowestValue + (highestValue - lowestValue) * rand(N)
% Zero out first and last rows.
theMatrix(1,:) = 0;
theMatrix(end,:) = 0;
% Zero out first and last columns.
theMatrix(:,1) = 0;
theMatrix(:,end) = 0;

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jimaras 2013-10-13

I want to create two NxN matrices whose values can be between 0 and 5. I want later to implement these matrices in a prey & predator model so I think it's important to have values of 0 and of 5.

Image Analyst 2013-10-13

编辑：Image Analyst 2013-10-13

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Like I said in the code, just change lowestValue:

lowestValue = 0;

What about the requirement that the outer edges of the array be zero? Recall where you said "the columns 1 and 2002 and the rows 1 and 2002 to be 0 " - to me, that means that column 1 and column 2002 (or the last column if N is different that 2002) should equal exactly 0. And the same for the first and last row - they are all zero. Again, is this still required? If not, just don't do the zeroing out and do:

N = 2002; % Whatever you want
lowestValue = 0; % or 1 - whichever you want.
highestValue = 5;
theMatrix = lowestValue + (highestValue - lowestValue) * rand(N)

Essentially (in an inflexible, hard coded manner):

theMatrix = 5 * rand(2002)

Did you follow what I said in my prior comment about never being able to hit any particular number exactly ?

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