How to push a datetime var or a demical var to a .NET SOAP server using PHP?

Question

I am sending all the parameters needed to the SOAP server, but they require one of the params to be a decimal and one to be a datetime. I can't figure out how to convert a string to either type.

<?php

$params = array(

 # this converts the string to an int
 'int'  => (int) '123', 

 # to datetime is a big ? to me
 'day' => date("n/j/Y",time() - 128000),

 # to datetime is a big ? to me
 'end'  => date("n/j/Y",time() + 64000),

 # to decmial is a big ? to me
 'amt' => 2.44,

 # this converts the int to a string
 'str' => (string) 100,
);
?>

So how does PHP do something like this (below) in SOAP?

<?php
echo (decmial) 2.44;
echo (datetime) time();
?>