My Biorhythm

<?php
    // Biorhythm
    //
    // Print a standard page header
    //
    function pageHeader() {
        global $TEXT;
        echo '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"'."\n";
        echo '    "http://www.w3.org/TR/html4/loose.dtd">'."\n";
        echo "<html><head>";
        echo '<link href="xampp.css" rel="stylesheet" type="text/css">';
        echo '<meta name="author" content="My Biorhythm">';
        echo "<title>My Biorhythm</title>";
        echo "</head><body>";

echo "<br><h1>My Biorhythm</h1>";
 
    }

//
    // Print a standard page footer
    //
    function pageFooter() {
    echo "<br><br>The charts display a period of 2 days before and 32 days after the target date.<br>
Positive periods of the cycle indicate high ability days and its negative periods show low ability days. Near zero means critical days.<br>
<br>
It is said that human body has three rhythms with a fixed cycle.<br>
1. <font color='0000ff'><b>Physical</b></font> biorhythm (23-day cycles) is related to physical strength, durability, resistance, stamina, courage and etc..<br>
2. <font color='ff0000'><b>Emotional</b></font> biorhythm (28-day cycles) is related to emotional stability, feeling, intuition, mood, susceptibility, creativity and etc.<br>
3. <font color='00ff00'><b>Intellectual</b></font> biorhythm (33-day cycles) is related to thinking, analyzing, judgment, concentration, composition and etc.</body></html>";
    }

//
    // Function to draw a curve of the biorythm
    // Parameters are the day number for which to draw,
    // period of the specific curve and its color
    //
    
    function drawRhythm($daysAlive, $period, $color) {
        global $daysToShow, $image, $diagramWidth, $diagramHeight;

// get day on which to center
        $centerDay = $daysAlive - ($daysToShow / 2);

// calculate diagram parameters
        $plotScale = ($diagramHeight - 25) / 2;
        $plotCenter = ($diagramHeight - 25) / 2;

// draw the curve
        for ($x = 0; $x <= $daysToShow; $x++) {
            // calculate phase of curve at this day, then Y value
            // within diagram
            $phase = (($centerDay + $x) % $period) / $period * 2 * pi();
            $y = 1 - sin($phase) * (float)$plotScale + (float)$plotCenter;

// draw line from last point to current point
            if ($x > 0) {
                imageLine($image, $oldX, $oldY, $x * $diagramWidth / $daysToShow, $y, $color);
            }

// save current X/Y coordinates as start point for next line
            $oldX = $x * $diagramWidth / $daysToShow;
            $oldY = $y;
        }
    }

//
    // ---- MAIN PROGRAM START ----
    //

// check if we already have a date to work with,
    // if not display a form for the user to enter one
    //
    
    if (!isset($_REQUEST['birthdate'])) {
        pageHeader();
?>
        <form method="post" action="<?php echo basename($_SERVER['PHP_SELF']); ?>">
            
           Please Enter Your Birthday:
            <br>
            <input type="text" name="birthdate" value="MM/DD/YYYY"><p>
            <input type="submit" value="<?php echo $TEXT['bio-ok']; ?>">
            <input type="hidden" name="showpng" value="1">
        </form>
<?php
        include 'showcode.php';

pageFooter();
        exit;
    }

// get different parts of the date
    $birthMonth = substr($_REQUEST['birthdate'], 0, 2);
    $birthDay = substr($_REQUEST['birthdate'], 3, 2);
    $birthYear = substr($_REQUEST['birthdate'], 6, 4);

// check date for validity, display error message if invalid
    if (!@checkDate($birthMonth, $birthDay, $birthYear)) {
        pageHeader();

//print("The date '$birthMonth/$birthDay/$birthYear' is invalid.");
        echo "<h2>".$TEXT['bio-error1']." '$birthMonth/$birthDay/$birthYear' ".$TEXT['bio-error2'].".</h2>";

pageFooter();
        exit;
    }

if (isset($_POST['showpng']) && ($_POST['showpng'] == 1)) {
        pageHeader();

echo "<img src='".basename($_SERVER['PHP_SELF'])."?".htmlentities("birthdate=".urlencode($_REQUEST['birthdate']))."' alt=''>";

pageFooter();
        exit;
    }

// specify diagram parameters (these are global)
    $diagramWidth = 710;
    $diagramHeight = 400;
    $daysToShow = 30;

// calculate the number of days this person is alive
    // this works because Julian dates specify an absolute number
    // of days -> the difference between Julian birthday and
    // "Julian today" gives the number of days alive
    
    $daysGone = abs(gregorianToJD($birthMonth, $birthDay, $birthYear) - gregorianToJD(date("m"), date("d"), date("Y")));

// create image
    $image = imageCreate($diagramWidth, $diagramHeight);

// allocate all required colors
    $colorBackgr = imageColorAllocate($image, 192, 192, 192);
    $colorForegr = imageColorAllocate($image, 255, 255, 255);
    $colorGrid = imageColorAllocate($image, 0, 0, 0);
    $colorCross = imageColorAllocate($image, 0, 0, 0);
    $colorPhysical = imageColorAllocate($image, 0, 0, 255);
    $colorEmotional = imageColorAllocate($image, 255, 0, 0);
    $colorIntellectual = imageColorAllocate($image, 0, 255, 0);

// clear the image with the background color
    imageFilledRectangle($image, 0, 0, $diagramWidth - 1, $diagramHeight - 1, $colorBackgr);

// calculate start date for diagram and start drawing
    $nrSecondsPerDay = 60 * 60 * 24;
    $diagramDate = time() - ($daysToShow / 2 * $nrSecondsPerDay) + $nrSecondsPerDay;

for ($i = 1; $i < $daysToShow; $i++) {
        $thisDate = getDate($diagramDate);
        $xCoord = ($diagramWidth / $daysToShow) * $i;

// draw day mark and day number
        imageLine($image, $xCoord, $diagramHeight - 25, $xCoord, $diagramHeight - 20, $colorGrid);
        imageString($image, 3, $xCoord - 5, $diagramHeight - 16, $thisDate["mday"], $colorGrid);

$diagramDate += $nrSecondsPerDay;
    }

// draw rectangle around diagram (marks its boundaries)
    imageRectangle($image, 0, 0, $diagramWidth - 1, $diagramHeight - 20, $colorGrid);

// draw middle cross
    imageLine($image, 0, ($diagramHeight - 20) / 2, $diagramWidth, ($diagramHeight - 20) / 2, $colorCross);
    imageLine($image, $diagramWidth / 2, 0, $diagramWidth / 2, $diagramHeight - 20, $colorCross);

// print descriptive text into the diagram
    imageString($image, 3, 10, 10,  " Bio Birthday : $birthMonth / $birthDay / $birthYear", $colorCross);
    imageString($image, 3, 10, 26,  " Bio Today's Date : ".date("M d, Y"), $colorCross);
    imageString($image, 3, 10, $diagramHeight - 42, $TEXT['bio-physical'], $colorPhysical);
    imageString($image, 3, 10, $diagramHeight - 58, $TEXT['bio-emotional'], $colorEmotional);
    imageString($image, 3, 10, $diagramHeight - 74, $TEXT['bio-intellectual'], $colorIntellectual);

// now draw each curve with its appropriate parameters
    drawRhythm($daysGone, 23, $colorPhysical);
    drawRhythm($daysGone, 28, $colorEmotional);
    drawRhythm($daysGone, 33, $colorIntellectual);

// set the content type
    header("Content-Type: image/png");

// create an interlaced image for better loading in the browser
    imageInterlace($image, 1);

// mark background color as being transparent
    imageColorTransparent($image, $colorBackgr);

// now send the picture to the client (this outputs all image data directly)
    imagePNG($image);
    exit;
?>

The charts display a period of 2 days before and 32 days after the target date.
Positive periods of the cycle indicate high ability days and its negative periods show low ability days. Near zero means critical days.

It is said that human body has three rhythms with a fixed cycle.
1. Physical biorhythm (23-day cycles) is related to physical strength, durability, resistance, stamina, courage and etc..
2. Emotional biorhythm (28-day cycles) is related to emotional stability, feeling, intuition, mood, susceptibility, creativity and etc.
3. Intellectual biorhythm (33-day cycles) is related to thinking, analyzing, judgment, concentration, composition and etc.