Core PHP
A Trigonometric Function Graphing Form
This PHP example program demonstrates how to create a form to display trigonometric function graphs.
GraphFunctionForm.php
<!DOCTYPE>
<html>
<head>
<title>Graphing Form</title>
</head>
<body>
<div style="width:604px;background-color:#F8F8F8;border:2px darkgray outset;padding:5px;">
<form action="<?php echo $_SERVER['PHP_SELF'] ?>" method="post">
<fieldset>
<legend>Function Graphing</legend>
<label for="fn">Function:</label>
<select name="fn">
<option value="sin" <?php echo ((isset($_POST['fn']) && ($_POST['fn'] == 'sin')) ? "selected" : ""); ?>>Sin</option>
<option value="cos" <?php echo ((isset($_POST['fn']) && ($_POST['fn'] == 'cos')) ? "selected" : ""); ?>>Cos</option>
<option value="tan" <?php echo ((isset($_POST['fn']) && ($_POST['fn'] == 'tan')) ? "selected" : ""); ?>>Tan</option>
<option value="csc" <?php echo ((isset($_POST['fn']) && ($_POST['fn'] == 'csc')) ? "selected" : ""); ?>>Csc</option>
<option value="sec" <?php echo ((isset($_POST['fn']) && ($_POST['fn'] == 'sec')) ? "selected" : ""); ?>>Sec</option>
<option value="cot" <?php echo ((isset($_POST['fn']) && ($_POST['fn'] == 'cot')) ? "selected" : ""); ?>>Cot</option>
</select><br /><br />
<fieldset>
<legend>Range of x</legend>
<input id="idLowX" type="number" name="lowx" step="0.01"
value="<?php echo (isset($_POST['lowx']) ? $_POST['lowx'] : '-3.14') ?>" />
<input id="idHighX" type="number" name="highx" step="0.01"
value="<?php echo (isset($_POST['highx']) ? $_POST['highx'] : '3.14') ?>" /><br />
</fieldset>
<fieldset>
<legend>Range of y</legend>
<input id="idLowY" type="number" name="lowy" step="0.01"
value="<?php echo (isset($_POST['lowy']) ? $_POST['lowy'] : '-3.14') ?>" />
<input id="idHighY" type="number" name="highy" step="0.01"
value="<?php echo (isset($_POST['highy']) ? $_POST['highy'] : '3.14') ?>" /><br />
</fieldset><br />
<input name="FnSubmit" type="submit" value="Graph">
</fieldset>
</form>
<div style="width:604px;height:604px;">
<?php
include 'CGraphYEqFX.php';
if (array_key_exists('FnSubmit', $_POST)) {
$qGraph = new CGraphYEqFX(600, 600,
floatval($_POST['lowx']), floatval($_POST['lowy']),
floatval($_POST['highx']), floatval($_POST['highy']));
$qGraph->DrawGridLines(M_PI/8, M_PI/8);
$qGraph->GraphFunction($_POST['fn']);
echo '<img style="border:2px darkgray inset;" src="data:image/png;base64,'.base64_encode($qGraph->GetImageData()).'">';
}
?>
</div>
</div>
</body>
</html>
Output
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