function BMI(){

                cm = document.bmi.cm.value;

                // if (!(foot > 0)) alert ("You must fill in the \"feet\" box with a number.");

                kg = document.bmi.kg.value;

                // if (!(pounds > 0)) alert ("You must fill in the \"weight\" box with a number.");  

                index = cm*cm*.0001 //height in meters

                index = kg/ index;

                index = Math.round(index*10)/10; 

                if (!index) index = " ";

                document.bmi.result.value = index;

        }