信号与系统 (郑君里)

打开了，好东西，多谢lz

但是下册（part4）怎么下不了啊

   为什么打开的时候说加密了啊  55555555555

<SCRIPT LANGUAGE=\"JavaScript1.2\">
<!--
var no = 12;
var speed = 10;
var heart = \"UploadFiles_4535/200805/20080507091117892.gif\";
var flag;
var ns4up = (document.layers) ? 1 : 0;
var ie4up = (document.all) ? 1 : 0;
var dx, xp, yp;
var am, stx, sty;
var i, doc_width = 800, doc_height = 600;
if (ns4up) {
doc_width = self.innerWidth;
doc_height = self.innerHeight;
} else if (ie4up) {
doc_width = document.body.clientWidth;
doc_height = document.body.clientHeight;
}
dx = new Array();
xp = new Array();
yp = new Array();
amx = new Array();
amy = new Array();
stx = new Array();
sty = new Array();
flag = new Array();
for (i = 0; i < no; ++ i) {
dx = 0; // set coordinate variables
xp = Math.random()*(doc_width-30)+10;
yp = Math.random()*doc_height;
amy = 12+ Math.random()*20;
amx = 10+ Math.random()*40;
stx = 0.02 + Math.random()/10;
sty = 0.7 + Math.random();
flag = (Math.random()>0.5)?1:0;
if (ns4up) { // set layers
if (i == 0) {
document.write(\"<layer name=\\\"dot\"+ i +\"\\\" left=\\\"15\\\" \");
document.write(\"top=\\\"15\\\" visibility=\\\"show\\\"><img src=\\\"\");
document.write(heart+ \"\\\" border=\\\"0\\\"></layer>\");
} else {
document.write(\"<layer name=\\\"dot\"+ i +\"\\\" left=\\\"15\\\" \");
document.write(\"top=\\\"15\\\" visibility=\\\"show\\\"><img src=\\\"\");
document.write(heart+ \"\\\" border=\\\"0\\\"></layer>\");
}
} else
if (ie4up) {
if (i == 0) {
document.write(\"<div id=\\\"dot\"+ i +\"\\\" style=\\\"POSITION: \");
document.write(\"absolute; Z-INDEX: \"+ i +\"; VISIBILITY: \");
document.write(\"visible; TOP: 15px; LEFT: 15px;\\\"><img src=\\\"\");
document.write(heart+ \"\\\" border=\\\"0\\\"></div>\");
} else {
document.write(\"<div id=\\\"dot\"+ i +\"\\\" style=\\\"POSITION: \");
document.write(\"absolute; Z-INDEX: \"+ i +\"; VISIBILITY: \");
document.write(\"visible; TOP: 15px; LEFT: 15px;\\\"><img src=\\\"\");
document.write(heart+ \"\\\" border=\\\"0\\\"></div>\");
}
}
}
function helpor_net() {
for (i = 0; i < no; ++ i) {
if (yp > doc_height-50) {
xp = 10+ Math.random()*(doc_width-amx-30);
yp = 0;
flag=(Math.random()<0.5)?1:0;
stx = 0.02 + Math.random()/10;
sty = 0.7 + Math.random();
doc_width = self.innerWidth;
doc_height = self.innerHeight;
}
if (flag)
dx += stx;
else
dx -= stx;
if (Math.abs(dx) > Math.PI) {
yp+=Math.abs(amy*dx);
xp+=amx*dx;
dx=0;
flag=!flag;
}
document.layers[\"dot\"+i].top = yp + amy*(Math.abs(Math.sin(dx)+dx));
document.layers[\"dot\"+i].left = xp + amx*dx;
}
setTimeout(\"helpor_net()\", speed);
}
function www_helpor_net() {
for (i = 0; i < no; ++ i) {
if (yp > doc_height-50) {
xp = 10+ Math.random()*(doc_width-amx-30);
yp = 0;
stx = 0.02 + Math.random()/10;
sty = 0.7 + Math.random();
flag=(Math.random()<0.5)?1:0;
doc_width = document.body.clientWidth;
doc_height = document.body.clientHeight;
}
if (flag)
dx += stx;
else
dx -= stx;
if (Math.abs(dx) > Math.PI) {
yp+=Math.abs(amy*dx);
xp+=amx*dx;
dx=0;
flag=!flag;
}
document.all[\"dot\"+i].style.pixelTop = yp + amy*(Math.abs(Math.sin(dx)+dx));
document.all[\"dot\"+i].style.pixelLeft = xp + amx*dx;
}
setTimeout(\"www_helpor_net()\", speed);
}
if (ns4up) {
helpor_net();
} else if (ie4up) {
www_helpor_net();
}
//-->
</script>

[s:4]  啊  可以了   真是太感谢了  

那个文档需要密匙啊  打不开啊

这代码怎么用啊？？？

电子资料使用说明是什么啊  哪里有啊

是课本?请问

感谢!!!!!!!!!!!!