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

Answer 1

[Dr. Seis]

>> 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.

[catarina]

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

[Dr. Seis]

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?

[Dr. Seis]

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).