var fDesc=new Array(); fDesc[0] = "This applet allows students to understand the process of convolution. First they create a signal and a filter function to convolve. Then, they place the filter function when they see the product function of the two original signals. In a final graph below, they build up the convolution, seeing the area under the product curve correspond to the value of the convolution at that point."; 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 = ''; } }