How to randomly generate 0.1 or -0.1?

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Ricardo Gutierrez
Ricardo Gutierrez 2018-4-23
评论： Ricardo Gutierrez 2018-4-23
Hello. Good day. I have this code:
for sm=0:0.1:0.1
f=sm*eye(N)
end
I get the following: f =
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
f =
0.1000 0 0 0 0 0 0 0 0 0
0 0.1000 0 0 0 0 0 0 0 0
0 0 0.1000 0 0 0 0 0 0 0
0 0 0 0.1000 0 0 0 0 0 0
0 0 0 0 0.1000 0 0 0 0 0
0 0 0 0 0 0.1000 0 0 0 0
0 0 0 0 0 0 0.1000 0 0 0
0 0 0 0 0 0 0 0.1000 0 0
0 0 0 0 0 0 0 0 0.1000 0
0 0 0 0 0 0 0 0 0 0.1000
I want to obtain the following: f =
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
f =
-0.1000 0 0 0 0 0 0 0 0 0
0 0.1000 0 0 0 0 0 0 0 0
0 0 -0.1000 0 0 0 0 0 0 0
0 0 0 -0.1000 0 0 0 0 0 0
0 0 0 0 0.1000 0 0 0 0 0
0 0 0 0 0 0.1000 0 0 0 0
0 0 0 0 0 0 0.1000 0 0 0
0 0 0 0 0 0 0 -0.1000 0 0
0 0 0 0 0 0 0 0 0.1000 0
0 0 0 0 0 0 0 0 0 -0.1000
As we can see, we generated 0.1 and -0.1 randomly. That's what I want randomly generated 0.1 and -0.1 I hope I have explained my question well. Greetings and thanks.

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Stephen23
Stephen23 2018-4-23
diag((2*randi(0:1,1,N)-1)/10)
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Stephen23
Stephen23 2018-4-23

" Using this code that you did how to previously generate the matrix... and then the random matrix (0.1 or -0.1)"

It really works the other way around: first it generates a vector of random values, and then uses diag to form a matrix, placing those values along the diagonal. I am sure that you can read the randi and diag help to know what they do, and try the parts of the code yourself:

>> N = 6;
>> randi(0:1,1,N)
ans =
     1     0     1     0     0     0
>> (2*randi(0:1,1,N)-1)/10
ans =
          0.1          0.1         -0.1         -0.1         -0.1          0.1
>> diag((2*randi(0:1,1,N)-1)/10)
ans =
          0.1            0            0            0            0            0
            0          0.1            0            0            0            0
            0            0         -0.1            0            0            0
            0            0            0          0.1            0            0
            0            0            0            0          0.1            0
            0            0            0            0            0         -0.1
Ricardo Gutierrez
Ricardo Gutierrez 2018-4-23
It is understood. Thank you very much

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