Using the find function

I am trying to pull out a certain value in this function. I am trying to find the values of the wbar(i,1),wbar(i,2), and wbar(i,3) each at M=0,0.5,1,and 5. I can get it to work at M=0 and M=5 but not between. Can anyone help with this?

Here is my code:

n = 100;
M = linspace(0,5,n);

wbar = NaN(n,3);

wbar(1,:) = [pi/2,3*pi/2,5*pi/2];

for i=2:n

    fun = @(w) cos(w) - M(i)*sin(w);
      wbar(i,1) = fzero(fun,wbar(i-1,1));
      wbar(i,2) = fzero(fun,wbar(i-1,2));
      wbar(i,3) = fzero(fun,wbar(i-1,3));
  end
  figure(1)
  plot(M,wbar,'-')
  grid on

index = find(M==2);
freq1=wbar(index,1)

index = find(M==2);
freq2=wbar(index,2)

index = find(M==2);
freq3=wbar(index,3)

[Denikka Brent]

Note: I have M==2 just to see if it will work for any values between 0 and 5

Answer 1

[madhan ravi]

index = (M>2&M<5); %M greater than 2 and less than 5

Logical indexing is efficient

[Denikka Brent]

Thanks!

[madhan ravi]

Anytime :)