var fDesc=new Array();
fDesc[0] = "LSI Convolution is a very helpful tool for students.<br /> Two key properties in signal processing are &quot;linearity&quot; and &quot;spatial invariance&quot;. Students can examine these properties by placing and scaling two impulse functions and then dragging a filter function over them (just as in the Impulse Response applet).";

function tShowHide(id, show)
{
	var s = document.getElementById("desc");

	if ((s.innerHTML.length<=212 || show==1) && show!=2)
	{
		s.innerHTML = fDesc[id];
		if (document.getElementById('m1'))
			document.getElementById('m1').style.display='none';
		if (document.getElementById('m2'))
			document.getElementById('m2').style.display='none';
		if (document.getElementById('more_txt'))
			document.getElementById('more_txt').style.display='inline';
	}
	else
	{
		s.innerHTML = '';
	}
}