Usuário:Gustavob/teste.js

    <script type="text/javascript">

      // the algorithm is implemented inside out so we can control our CPU usage
      // rather than the main loop squareing the current guess we run one iteration
      // and call result() when we are finished

      function write(digit) {
        document.body.appendChild(document.createTextNode(digit));
      }

      function writeLine(str) {
	document.body.appendChild(document.createElement("br"));
	document.body.appendChild(document.createTextNode(str));
      }

      var r = [];
      // the working result of n * n, used to check estimates of n * n

      var i = 0;
      // index into n as we compute n * n
      var j = 0;
      // index into n as we compute n * n

      var min = 0;
      // min next last digit
      var max = 10;
      // one larger than max last digit
      // min and max used to binary search for next digit
       
      var n = [Math.floor((min + max)/2)];
      // the sqrt(2) computed so far, last digit is working value
      // base ten array, e.g. 1.414 = [1, 4, 1, 4]

      function run() {
           // work for 1/10 sec then pause for a while
           // so we don't use up all available CPU and make
           // the browser unresponsive
           var startTime = new Date().getTime();
           var startLen = n.length;
           while (true) {
               for (var steps = 0; steps < 100; ++steps) {
                   process();
	           if (n.length != startLen) {
		       // setTimeout if results changes so we see early digits immediately
                       break;
	           }
               }
               var now = new Date().getTime();
               var ms = now - startTime;
               if (ms > 100 || n.length != startLen) {
		    //;;writeLine(ms);
                    setTimeout("run();", ms * (Math.SQRT2 - 1));
                    // pause for sqrt(2)-1 of the time we have taken
                    // this will make us use 1/sqrt(2) of the one CPU (70.7%)
	            return;
               }
           }
      }

      function process() {

	    // 1.4 = [1, 4]
	    // 1x1 = 1, 0.4*0.4 = .16, 0.01*0.01 = 0.0001, 0.1*0.02 = 0.002
	    //;;writeLine("");
	    //;;writeLine("process()");
            //;;writeLine("n = [" + n + "]");
            //;;writeLine("r = [" + r + "]");
	    //;;writeLine("i = " + i);
	    //;;writeLine("j = " + j);
            var dest = i + j;
	    //;;writeLine("dest = " + dest);
            var e = n[i] * n[j];
	    while (r.length <= dest) {
	      r.push(0);
	    }
            //;;writeLine("e = " + e)
            for (; e != 0; --dest) {
 	      //;;writeLine("dest = " + dest);
	      if (dest < 0) {
	         // only one whole number digit
	         // e.g. 25.2 = [25, 2]
	         r[0] += e * 10;
	         break;
	      }		
  	      r[dest] += e;
	      //;;writeLine("r[dest] = " + r[dest]);
	      e = Math.floor(r[dest] / 10);
	      //;;writeLine("e = " + e)
	      r[dest] = r[dest] % 10;
              //;;writeLine("r[dest] = " + r[dest])
            } // while carrying digits

	    //;;writeLine("r = [" + r + "]");

            if (++j == n.length) {
               j = 0;
               if (++i == n.length)  {
                   result(r);
                   r = [];
	           i = 0;
               }
           }
      } // function squareStep()

     function result(r) {
	//;;writeLine("");
	//;;writeLine("");
        //;;writeLine("result(" + r + ")");
        var digit = n.length - 1;
        if (r[0] >= 2) {
	    max = n[digit];
	    //;;writeLine("too big, max = " + max);
        } else {
            min = n[digit];
	    //;;writeLine("ok, at least, min = " + min);
        }
        //;;writeLine("min = " + min);
        //;;writeLine("max = " + max);
        if (min + 1 == max) {
            n[digit] = min;
            gotDigit(n.length, n[digit]);
	    min = 0;
	    max = 10;
            n.push(Math.floor((min + max)/2));
	} else {
            n[digit] = Math.floor((min + max)/2);
        }
        //;;writeLine("next try = last digit = " + n[n.length - 1]);
     }

      var val = document.getElementById("val")

      var setElementWorks = true;
	// with IE document.createElement("font").setElement("style", "color: white") is ignored
	// have to use non-standard createElement("<font style=\"color: white\">") which doesn't work in Firefox

      var shyWorks = true;
	// with Firefox soft-hyphen "\xAD"/&shy; is ignored and won't break into lines
        // have to use " " with font-size 0.1

      if (navigator.userAgent.indexOf("MSIE") != -1) {
        // IE: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322)        
	setElementWorks = false;
      } else if (navigator.userAgent.indexOf("Gecko") != -1) {
        // Firefox: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.0.3) Gecko/20060523 Ubuntu/dapper Firefox/1.5.0.3
	shyWorks = false; 
      } else {
        // others
	// be pesamistic about &shy; working (using workaround works in all browers)
	shyWorks = false; 
        // but assume standards compliant with .setElement()
      }

      function gotDigit(num, d) {
	
	//;;writeLine("");
	//;;writeLine("");
	//;;writeLine("");
        //;;writeLine("gotDigit(" + num + ", " + d + ")");

        var t = document.createTextNode(d)
	//t.appendData("\xAD");
	val.appendChild(t);
	//val.appendChild(document.createElement("br"));
        //document.write(n[digit]);
        ///document.write("&shy;");

	// &shy; soft hyphen is ignored in firefox and won't be broken into lines
        // text in font-size < 0.1 is removed and won't be broken into lines
	if (setElementWorks) {
          shy = document.createElement("font");
          shy.setAttribute("style", "font-size: 0.1; color: white");
        } else {
	  shy = document.createElement("<font style=\"font-size: 0.1; color: white\">");
	}

        if (shyWorks) {
          shy.appendChild(document.createTextNode("\xAD"));
 	  // U+AD = HTML &shy; = soft-hyphen
	  // createTextNode() takes plain text not HTML
	  // createEntityReference() is W2C but not in IE
        } else {
	   shy.appendChild(document.createTextNode(" "));
        }
        val.appendChild(shy);

	if (num == 1) {
	  val.appendChild(document.createTextNode("."));
        }
    }

    run()

    </script>