Form validation class and summation function

[kr1pt]

Hello everyone. I'm new so I'm still reading the rules, but... I have a couple scripts, libraries and other PHP apps on my PC, and those scripts are just collecting dust on PC so I will post some of them in here. Please comment scripts Pretty good for 15 years old kid? :$

 

Summation function:

<?php

/**
* Summation of m numbers
* 
* @param integer $m
* @param integer $n
* @param string $parameter Terms of summation
* @param string $parameter_delimiter
* @return integer
*/
function sum($m = 0, $n = 1, $parameter = 'n', $parameter_delimiter = 'n')
{
    if ($m === 0 or is_numeric($m) === FALSE)
    {
        return 0;
    }

    if ($n == 0 or is_numeric($n) === FALSE)
    {
        $n = 1;
    }

    if ($parameter == '' or is_numeric($parameter) === TRUE)
    {
        $parameter = 'n';
    }

    if ($parameter_delimiter == '' or is_numeric($parameter_delimiter) === TRUE or strlen($parameter_delimiter) > 1)
    {
        $parameter_delimiter = 'n';
    }

    $result = 0;

    for ($x = 1; $x <= $m; $x++)
    {
        $i = $x * $n;

        $param = str_replace($parameter_delimiter, $i, $parameter);

        $result += eval('return ' . $param . ';');
    }

    return (int)$result;
}

// example:
// (1+1) + (2+1) + (3+1) + (4+1) + (5+1)
echo sum(5, 1, 'n+1');

// example 2:
// (2+1) + (4+1) + (6+1) + (8+1) + (10+1)
echo sum(5, 2, 'n+1');

// you can also use n/2, n*sqrt(2) or other...

 

PHP form validation library-class:

http://www.2shared.com/file/7v2IzMfM/Form.html

 

Everything is explained in index.php, such as configuration and stuff.

Still working on security in that class.