function calculate_angle(){

  // check to see if user entered a value for hours and minutes

  if (document.form.hours.value == "" || document.form.hours.length == "0"){
    alert("You must enter a value for hours");
    return;
  }
  if (document.form.mins.value =="" || document.form.mins.length == "0"){
    alert("You must enter a value for minutes");
    return;
  }

  var hours = document.form.hours.value;
  var mins = document.form.mins.value;
  // var secs = document.form.secs.value;
  var angle;

  // check to see if user entered numbers for hours and minutes //

  var i;

  for(i=0; i < hours.length; ++i){
    if( (hours.charCodeAt(i) < 48) ||  (hours.charCodeAt(i) > 57 ) ){
      alert("You must enter a POSITIVE INTEGER for hours");
      return;
    }
  } 
  for(i=0; i < mins.length; ++i){
    if( (mins.charCodeAt(i) < 48) || (mins.charCodeAt(i) > 57) ){
      alert("You must enter a POSITIVE INTEGER for minutes");
      return;
    }
  }

  // check to see if user enter proper values for hours and minutes

  if ( (hours < 1) || (hours > 12) ){
    alert("You must enter a valid hour");
    return;
  }
  if ( (mins < 1) || (mins > 59) ){
    alert("You must enter a valid minute");
    return;
  }

  // calculate angle inbetween hour and minute hand 

  angle = Math.abs( (30*hours) - (6*mins) );

  if (angle > 180){
    angle = 360 - angle;
  }  

  document.form.angle.value = angle;

}

function calculate_angle2(){

  // check to see if user entered a value for hours and minutes

  if (document.form2.hours.value == "" || document.form2.hours.length == "0"){
    alert("You must enter a value for hours");
    return;
  }
  if (document.form2.mins.value =="" || document.form2.mins.length == "0"){
    alert("You must enter a value for minutes");
    return;
  }
  if (document.form2.secs.value =="" || document.form2.secs.length =="0"){
    alert("You must enter a value for seconds");
    return;
  }

  var hours = document.form2.hours.value;
  var mins = document.form2.mins.value;
  var secs = document.form2.secs.value;
  var angle;

  // check to see if user entered numbers for hours, minutes, and seconds //

  var i;
  for(i=0; i < hours.length; ++i){
    if( (hours.charCodeAt(i) < 48) ||  (hours.charCodeAt(i) > 57 ) ){
      alert("You must enter a POSITIVE INTEGER for hours");
      return;
    }
  } 
  for(i=0; i < mins.length; ++i){
    if( (mins.charCodeAt(i) < 48) || (mins.charCodeAt(i) > 57) ){
      alert("You must enter a POSITIVE INTEGER for minutes");
      return;
    }
  }
  for(i=0; i < secs.length; ++i){
    if( (secs.charCodeAt(i) < 48) || (secs.charCodeAt(i) > 57) ){
      alert("You must enter a POSITIVE INTEGER for seconds");
      return;
    }
  }

  // check to see if user enter proper values for hours and minutes

  if ( (hours < 1) || (hours > 12) ){
   alert("You must enter a valid hour");
    return;
  }
  if ( (mins < 0) || (mins > 59) ){
    alert("You must enter a valid minute");
    return;
  }
  if ( (secs < 0) || (secs > 59) ){
    alert("You must enter a valid second");
    return;
  }
 
  // calculate angle inbetween hour and minute hand 

  var min_hand_angle = 6*mins + 6*(secs/60);
  var hour_hand_angle = 30*hours + 30*(mins/60) + 30*(secs/3600);

//  alert(min_hand_angle);
//  alert(hour_hand_angle);

  angle = Math.abs(hour_hand_angle - min_hand_angle);

  if(angle > 180){
    angle = 360 - angle;
  }
 
  document.form2.angle.value = angle;

}