MATLAB: How could I check that how many elements of x is inside y

MATLAB

Suppose I have

x = [2,7,8,11];

and

y = [1,2,4,5,7,8,9,12,15,21,27]

How could I check that how many elements of x is inside y?

You can use ismember:

>> x = [2,7,8,11];
>> y = [1,2,4,5,7,8,9,12,15,21,27];
>> ismember(x,y)
ans =
   1   1   1   0
>> sum(ismember(x,y))
ans =  3

x =linspace(0,L,100);
y =w0./(120*E*I*L)*(-5*x.^4+6*L^2*x.^2-L^4);
plot(x,y);

B2 = glmfit(x(c,:), y==2, 'binomial');

That is, your use of 1 and 2 is confusing it, so you need to convert those to 0 and 1.