Defining global variables

I’m trying to define variables based on which OS the user is using. I’d like to define the name and links to each app version, defined in functions.php. Eg

if (MobileDTS::is('ios')) {
	$appname = "iPhone app";
        $applink = "http://itunes.apple.com/applink";

} else if (MobileDTS::is('android')) {
        $appname = "Android app";
        $applink = "https://market.android.com/androidlink";
}

Once I have defined the variables, I’d like to print them in my template file eg.

<a href="<?php global $applink; echo $applink; ?>">Download the <?php global $appname; echo $appname; ?></a>

Is this possible?

http://wordpress.org/plugins/mobile-detector/