Question

I have used the trapezoidal membership function through matlab as shown here.

I have written the following in matlab:

>> x=1:5;
>> y=trapmf(x,[1 3 4 5]);

And, for y, I got the following results:

>> y

y =

         0    0.5000    1.0000    1.0000         0

My questions are as follows:

How do we read the vector y shown above? Does it show the degrees of memberships for the elements in the set x?

For example, can we say the following?

• The degree of membership of 1 in the set x is 0
• The degree of membership of 2 in the set x is 0.5000
  .
  .
  .etc

Thanks.

Answer 1

Yes.. you are rite… That is how u read y..
I can’t give any references for this but you can generally look at these wiki articles about fuzzy sets…

http://en.wikipedia.org/wiki/Membership_function_(mathematics)
http://en.wikipedia.org/wiki/Fuzzy_set