function ClearForm(form){

    form.weight.value = "";
    form.height.value = "";
    form.bmi.value = "";
    form.my_comment.value = "";

}

function bmi(weight, height) {

          bmindx=weight/eval(height*height);
          return bmindx;
}

function checkform(form) {

       if (form.weight.value==null||form.weight.value.length==0 || form.height.value==null||form.height.value.length==0){
            alert("\nPlease complete the form first");
            return false;
       }

       else if (parseFloat(form.height.value) <= 0||
                parseFloat(form.height.value) >=500||
                parseFloat(form.weight.value) <= 0||
                parseFloat(form.weight.value) >=500){
                alert("\nÀEst‡ usted seguro de los datos que ha introducido? \nPor favor compruebe si son correctos: \nel peso en kilogramos y la talla en cms.");
                ClearForm(form);
                return false;
       }
       return true;

}

function computeform(form) {

       if (checkform(form)) {

       yourbmi=Math.round(bmi(form.weight.value, form.height.value/100));
       form.bmi.value=yourbmi;

       if (yourbmi >65) {
          form.my_comment.value='SUPERSUPEROBESIDAD';
       }
	   
	   else if (yourbmi >50 && yourbmi <=65) {
          form.my_comment.value='SUPEROBESIDAD';
       }
	   
	   else if (yourbmi >39 && yourbmi <=50) {
          form.my_comment.value='OBESIDAD MORBIDA O SEVERA';
       }

       else if (yourbmi >34 && yourbmi <=39) {
          form.my_comment.value='OBESIDAD MODERADA';
       }

       else if (yourbmi >30 && yourbmi <=34) {
          form.my_comment.value='OBESIDAD LEVE';
       }

       else if (yourbmi >25 && yourbmi <=30) {
          form.my_comment.value='SOBREPESO';
       }

       else if (yourbmi >=20 && yourbmi <=25) {
          form.my_comment.value='NORMAL';
       }

       else if (yourbmi <20) {
          form.my_comment.value='POR DEBAJO DEL PESO RECOMENDADO';
       }

       }
       return;
}