Why is my if function not working?

I do not know why my if function is giving me all my outputs, can someone help?

function [butterAmount]=howMuchButter(toastThickness, toastArea)

   if (toastThickness < 0.5) && (toastArea<9);
          butterAmount= 'smallAmnt';
      elseif (toastThickness >= 0.5 && toastThickness <= 0.75) && (toastArea <= 16 && toastArea >= 9);
          butterAmount='medAmnt';
      elseif (toastThickness >0.75) && (toastArea >16);
          butterAmount='largeAmnt';
      else
          butterAmount='tooWeird';
      end
  end

[Walter Roberson]

What difficulty are you observing?

[Heather Wun]

I keep getting all four outputs in zyLab's MATLAB at the same time, yet in the MATLAB program when I input butterAmount(1,20) etc. it works.

[Image Analyst]

Attach the test code also to make it easy for us to run. What is "zyLab's MATLAB"? How is that different from the regular MATLAB that we run?

[Walter Roberson]

You are running the function four times, each time asking that the output be assigned to a variable and that the results be displayed (because you do not have a semi-colon on the end of the line asking to not display output). Four outputs is the expected answer.