How to write comments defining the elements in a 2d array?

Hello,
I want to write text defining the elements of my matrice but can't figure out how to do it. I need to write a matrice that has element 1 if An <= Yj <= An+1 ; 0 otherwise.
I don't know how to put these instruction about the elements into the matrice. Hope I'm making sense!
Anyone that can help?
Thanks
Catarina

回答(1 个)

>> Yj = rand(3,4)
Yj =
0.5447 0.4239 0.1753 0.2433
0.2167 0.8710 0.1654 0.1209
0.8463 0.2685 0.3614 0.5910
>> Zj = (Yj>=0.3).*(Yj<=0.7)
Zj =
1 1 0 0
0 0 0 0
0 0 1 1
Note the ".*" used for element-by-element multiplication. Just substitute the 0.3 and 0.7 for your values associated with An and An+1.

3 个评论

Hi Elige,
Thanks for your answer. I'm not sure I understand. I don't think I explained properly or maybe I did but am just not understanding what to do. So I need the write the Fnj={1 if An <= Yj <= An+1; 0 otheriwse} as the condition for a sigma summation. Hope I'm making sense? does it still apply what you wrote before?
Regards,
Catarina
It should work. I just showed an example of Yj (since I don't know what those values actually are), but as long as you substitute "An" and "An+1" for "0.3" and "0.7", respectively, then you should get the correct result.
Fnj = (An<=Yj).*(Yj<=(An+1))
You did want Fnj to be the same sized matrix as Yj, right?
Also, you can copy my example above and paste into your Matlab command window to see how things work. For example:
A = (Yj>=0.3)
will produce a logical matrix the same size as Yj, but will have values of 1 for elements of Yj that are >= to 0.3 and values of 0 otherwise.
B = (Yj<=0.7)
will produce a logical matrix the same size as Yj, but will have values of 1 for elements of Yj that are <= 0.7 and values of 0 otherwise. By multiplying each element in A by the corresponding element in B you essentially get the intersection of A and B (i.e., where A and B both equal 1).

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2012-1-4

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