var imagenumber = 3 ;
var randomnumber = Math.random() ;
var rand = Math.round( (imagenumber-1) * randomnumber) + 1 ;
urls = new Array;
images = new Array;
alts = new Array;
var url = urls[rand];
var image = images[rand];
var alt = alts[rand];
function lookme(form) {
var bmi;
  if(! checkform(form)) return false;
  comput(form);
  bmi = Math.round(form.weight.value*10000/eval(form.height.value*form.height.value));
  form.bmi.value= bmi;
  if (bmi >40) {
     form.nowstat.value="你太、太...太胖了";
  }else if (bmi >30) {
     form.nowstat.value="必须开始减肥了,听我的没错";
  }else if (bmi >27) {
     form.nowstat.value="你比较胖，赶快开始减肥计划吧！";
  }else if (bmi >22) {
     form.nowstat.value="稍胖，\n还要多多运动啊!:)";
  }else if (bmi >=21) {
     form.nowstat.value="你这可是魔鬼身材!! :))";
  }else if (bmi >=18) {
     form.nowstat.value="瘦了一点点，你应该多吃点东西啊!";
  }else if (bmi >=16) {
     form.nowstat.value="太瘦，快点大量吃东西吧!";
  }else {
     form.nowstat.value="前胸贴后背,你怎么像个电线杆子\n一点肉都没有,快找大夫看看吧!!";
  }
  return true;
}
function comput(form) {
  if(form.sex.options.selectedIndex == "0")
    form.legendweight.value = Math.round(50+(2.3*(form.height.value-152))/2.54);
  else
    form.legendweight.value = Math.round(45.5+(2.3*(form.height.value-152))/2.54);
}
function checkform(form){
  if(form.weight.value == null || form.weight.value.length ==0 ||
     form.height.value == null || form.height.value.length ==0) {
    alert("请输入信息!!!");
    return false;
  }
  if(form.weight.value <=0) {
    alert("输入错误.");
    return false;
  }
  if(form.weight.value >500) {
    alert("输入错误.");
    return false;
  }
  if(form.height.value <=0) {
    alert("身高不对?");
    return false;
  }
  if(form.height.value >=300) {
    alert("输入错了");
    return false;
  }
  return true;
}




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("\输入错误");
 return false;
 }
else if (parseFloat(form.height.value) <= 0||
parseFloat(form.height.value) >=250||
parseFloat(form.weight.value) <= 0||
parseFloat(form.weight.value) >=250){
alert("\输入错误");
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 >38) {
form.my_comment.value="太胖了";
}
else if (yourbmi >28 && yourbmi <=38) {
 form.my_comment.value="超重";
}
else if (yourbmi >25 && yourbmi <=28) {
form.my_comment.value="你已经发福了";
}
else if (yourbmi >20 && yourbmi <=25) {
form.my_comment.value="你的体重目前正常，但也要预防疾病啊！";
}
else if (yourbmi >=15 && yourbmi <=20) {
form.my_comment.value="有些骨感，";
}
 else if (yourbmi >=11 && yourbmi <15) {
 form.my_comment.value="太瘦了";
 }
 else if (yourbmi <11) {
 form.my_comment.value="按照生物学来说这种生物是不能生存的";
}
}
return;
}