function click() {       
  if (event.button==2) {       
     alert('感謝您的光臨.')       
    }       
  }       
  document.onmousedown=click       
function goHist(a) {        
    history.go(a);            
    }        
     
function getgsbutton(buttonGroup) {     
  for (var i = 0; i < buttonGroup.length; i++) {     
    if (buttonGroup[i].checked) {     
      return i     
      }     
    }     
  return 0     
  }     
     
function clear2(form) {     
  form.earth_lat.value = "";     
  form.earth_lon.value = "";     
  form.elevation.value = "";     
  form.skysat_lon1.value = "";     
  form.xazimuth.value = "";     
  form.cul_status.value="輸入新資料!";     
  }     
     
function clear1(form) {     
  form.skysat_lon1.value = "";     
  form.elevation.value = "";     
  form.xazimuth.value = "";     
  form.cul_status.value="請輸入衛星位置!";     
  }     
     
function compute(form) {     
  form.cul_status.value=""     
  if (form.earth_lat.value!="" && form.earth_lon.value!="" && form.skysat_lon1.value!="") {     
    sat = form.skysat_lon1.value;     
    var ld = sat - form.earth_lon.value;     
    var cos_esl = Math.cos(form.earth_lat.value/180*(22/7));     
    var cos_ld = Math.cos(ld/180*(22/7));     
    if (form.earth_lat.value>81.3 || ld>81.3 || (cos_esl*cos_ld)<0.151 || Math.abs(ld) > 81.3){      
      form.elevation.value = "";     
      form.xazimuth.value = "";     
      form.cul_status.value="接收天線位置超出衛星含蓋範圍!";     /*  alert("接收天線位置超出衛星含蓋範圍!")    */     
      }     
    else {     
      var up = cos_esl * cos_ld - 0.151;     
      var dn = Math.sqrt(1 - cos_esl * cos_esl * cos_ld * cos_ld);     
      var t1 = Math.atan(up/dn);     
      form.elevation.value=t1/3.1412*180;     
      var t1 = Math.tan(ld/180*22/7)/Math.sin(form.earth_lat.value/180*22/7);     
      var azimuth = Math.abs(Math.atan(t1)/3.1412*180);     
      window.status="";          
      var xt= form.earth_lon.value*1;     
      var s=sat*1;     
      form.cul_status.value="計算完成！"     
      form.xazimuth.value=180-azimuth     
      form.cul_status.value=form.cul_status.value+"<本計算未含磁偏角修正量！>";     
      }     
    }     
  else {     
    if (form.earth_lon.value=="") {     
      form.cul_status.value ="經度 ";     
      }   
    if (form.earth_lat.value=="") {     
      form.cul_status.value = form.cul_status.value+"緯度 ";     
      }
    if (form.skysat_lon1.value=="") {     
      form.cul_status.value= form.cul_status.value+"衛星位置.";     
      }     
    form.cul_status.value= "資料不全!請輸入" + form.cul_status.value + "。";     
    window.status="資料輸入錯誤!";     
    return;     
    }     
  }