if <expression 1>
   % Executes when the boolean expression 1 is true 
   if <expression 2>
      % Executes when the boolean expression 2 is true    
   end
end

a = 100;
b = 200;
   % check the boolean condition 
   if( a == 100 )

      % if condition is true then check the following 
      if( b == 200 )

         % if condition is true then print the following 
         fprintf('Value of a is 100 and b is 200\n' );
      end

   end
   fprintf('Exact value of a is : %d\n', a );
   fprintf('Exact value of b is : %d\n', b );

Value of a is 100 and b is 200
Exact value of a is : 100
Exact value of b is : 200