how to compare different matrix?

i want to compare two different matrix that has given below 'a' and 'b'

 a=[ 'X'       'Y'       'Z'
   30.4596   37.6811   93.0000
  154.6678  172.8173   91.0000
   44.7308  175.6077   94.0000
   90.8282  191.0239   91.0000
  149.5394  149.1930   70.0000];

 b=     'Z'
      [93.0000];

and now if 'a' has the value of 'b' in 3rd column of 'a', if this condition is satisfied than it should display corresponding remaining two value of that row, like this

c=[ 'X'       'Y'       'Z'
 30.4596   37.6811   93.0000];

Answer 1

[Image Analyst]

Try this vectorized approach:

a=[ ... %'X'       'Y'       'Z'
  30.4596   37.6811   93.0000
  154.6678  172.8173   91.0000
  44.7308  175.6077   94.0000
  90.8282  191.0239   91.0000
  149.5394  149.1930   70.0000];

b= ...    'Z'
  [93.0000];
tolerance = 0.00001;
% Subtract third columns
matches = abs(a(:,3) - b) < tolerance
% Extract matching rows.
c = a(matches, :)

[Matlab111]

sir, thanks a lot it's working....

[Matlab111]

sir, one more question, how to delete that " Empty matrix".

NOTE: In this case if the value is not matched ('a' and 'b') than it's showing Empty matrix, so how to delete that.

[Image Analyst]

You can do clear('c') but then you won't have it later when you need to check on c. I'd just check it whenever you need to and not delete it:

if ~isempty(c)
   % Some code
else
   % Maybe exit from the function or something???
end

Answer 2

[Geoff Hayes]

Arul - if we assume that your b matrix has floating point values (as opposed to integers), then you may have to compare each value of b with each value in the third column of a and consider them identical if their absolute difference is less than some tolerance. For example,

 tol = 0.00001;
 for k=1:length(b)
     valb = b(k);
     for m=1:size(a,1)
         vala = a(m);
         if abs(valb- vala) < tol
             % near identical!
             % do something with mth row of a

             % go to next element of b
             break;
          end
      end
 end

The above should provide a starting point from which you can elaborate on to solve your question.

[Matlab111]

thank you sir,,,