function tafla(){
  byrja = 1*document.all['byrja'].value;
  enda  = 1*document.all['enda'].value;
  bil   = 1*document.all['bil'].value;
  start = bil/2;
  summa = 0.0;
  parent.frames['nedri'].document.close();
  parent.frames['nedri'].document.writeln("<table>");
  parent.frames['nedri'].document.write("<tr>");
  parent.frames['nedri'].document.write("<td> <b>x</b> </td>");
  parent.frames['nedri'].document.write("<td> <b>sin(<i>x</i>)</b> </td>");
  parent.frames['nedri'].document.writeln("</tr>");
  for (i = start; i<enda; i = i+bil){
    parent.frames['nedri'].document.write("<tr>");
    parent.frames['nedri'].document.write("<td>",i,"</td>");
    parent.frames['nedri'].document.write("<td>",Math.sin(i),"</td>");
    parent.frames['nedri'].document.writeln("</tr>");
	summa = summa + Math.sin(i);
  }
  summa = summa * bil;
  parent.frames['nedri'].document.write("<tr>");
  parent.frames['nedri'].document.write("<td><b>Samtals</b></td>");
  parent.frames['nedri'].document.write("<td><b>",summa,"</b></td>");
  parent.frames['nedri'].document.write("</tr>");
  parent.frames['nedri'].document.write("</table>");
}