Make more efficient code for some jquery array split
<p>I am having fun with jquery, and wonder if you can help make my code more efficient. Below is the only working code I can do so far. Any other trial is not happy:</p>

<p><strong>HTML</strong></p>

<pre><code>&lt;div class="someparent"&gt;...&lt;p&gt;&lt;input type="text"  value="0 0 12 12" class="radius"&gt;&lt;/p&gt;&lt;/div&gt;
</code></pre>

<p><strong>JQUERY:</strong></p>

<pre><code>    $('input.radius').each(function() {
            var preview = $(this).parents('.someparent');   

            $(this).keyup(function() {
                var rad = $(this).val();

                c = rad.split(' ');
                tl = c[0] ? c[0] + 'px' : '';
                tr = c[1] ? c[1] + 'px' : '';
                bl = c[2] ? c[2] + 'px' : '';
                br = c[3] ? c[3] + 'px' : '';

                var radius = tl + ' ' +  tr + ' ' + bl + ' ' + br;              
                $(preview).css('border-radius', radius);
            });
            if ($(this).val()) {
                var rad = $(this).val();

                c = rad.split(' ');
                tl = c[0] ? c[0] + 'px' : '';
                tr = c[1] ? c[1] + 'px' : '';
                bl = c[2] ? c[2] + 'px' : '';
                br = c[3] ? c[3] + 'px' : '';

                var radius = tl + ' ' +  tr + ' ' + bl + ' ' + br;                  
                preview.css('border-radius', radius);
            }
     });
</code></pre>

<p>Basically the code wants to update dynamically the properties based on any input, while keeping its current state whenever available as default.
Thanks for any help</p>
