<?php
if (!session_id()) { session_start(); }
session_register("currentStart");
session_register("currentEnd");

print $HTTP_SESSION_VARS[$HTTP_GET_VARS["img"]];

#Get whatever the user has selected
if (isset($HTTP_GET_VARS["start"]))
$SelectedStart = $HTTP_GET_VARS["start"];
else if (isset($HTTP_SESSION_VARS["currentStart"]))
$SelectedStart = $HTTP_SESSION_VARS["currentStart"];
else
$SelectedStart = get_first_datestamp();

if (isset($HTTP_GET_VARS["end"]))
$SelectedEnd = $HTTP_GET_VARS["end"];
else if (isset($HTTP_SESSION_VARS["currentEnd"]))
$SelectedEnd = $HTTP_SESSION_VARS["currentEnd"];
else
$SelectedEnd = get_current_datestamp();

#Save as session variables to be used by other pages
$HTTP_SESSION_VARS["currentStart"] = $GLOBALS["currentStart"] = $SelectedStart;
$HTTP_SESSION_VARS["currentEnd"] = $GLOBALS["currentEnd"] = $SelectedEnd;

?>

<?
function get_current_datestamp(){

//get the current timestamp 
$currdate = gmdate("Ymd");
$currday = substr($currdate,6,2);
$currmonth = substr($currdate,4,2);
$curryear = substr($currdate,0,4);
$currdate_stamp = ($curryear . "-" . $currmonth . "-" . $currday);
return $currdate_stamp;

}//end of function get_current_datestamp; 

?>

<?
function get_first_datestamp(){

//get the current timestamp 
$currdate = gmdate("Ymd");
$currday = substr($currdate,6,2);
$currmonth = substr($currdate,4,2)-1;
$curryear = substr($currdate,0,4);
$currdate_stamp = ($curryear . "-" . $currmonth . "-" . $currday);
return $currdate_stamp;

}//end of function get_first_datestamp; 

?>

<form action="<?php echo $HTTP_SESSION_VARS["SCRIPT_NAME"] ?>">
 Start:
<input name="start" size=10 value="<?php echo $SelectedStart ?>"><BR>
 End: &nbsp;
<input name="end" size=10 value="<?php echo $SelectedEnd ?>">
<input type="submit" value="OK">
</form>


VoltsPerCell.php:  (Code for the chart)

session_start(); // This connects to the existing session 


if(isset($HTTP_COOKIE_VARS["users_resolution"]))
    $screen_res = $HTTP_COOKIE_VARS["users_resolution"];
else //means cookie is not found set it using Javascript
{
?>
<script language="javascript">
<!--
writeCookie();

function writeCookie() 
{

 var the_cookie = "users_resolution="+ screen.width +"x"+ screen.height;
 document.cookie=the_cookie

}
//-->
</script>
<?
}

$Selectedstart = $HTTP_SESSION_VARS["currentStart"];
$Selectedend = $HTTP_SESSION_VARS["currentEnd"];