if (parseInt(navigator.appVersion.substring(0,1))>=3) { //3.0 or greater.

  // allocate the images
  cartCoors = new Image();
  quad1 = new Image();
  quad2 = new Image();
  quad3 = new Image();
  quad4 = new Image();

  homeBlk = new Image();
  homeBlu = new Image();
  homeRed = new Image();

  chapBlk = new Image();
  chapBlu = new Image();
  chapRed = new Image();

  tutorBlk = new Image();
  tutorBlu = new Image();
  tutorRed = new Image();

  hwrkBlk = new Image();
  hwrkBlu = new Image();
  hwrkRed = new Image();

  syllBlk = new Image();
  syllBlu = new Image();
  syllRed = new Image();

  gradBlk = new Image();
  gradBlu = new Image();
  gradRed = new Image();

  // set the realtive base href
  base = "/~kentler/Fall97_101/Images/";
  quadBase = "/~kentler/Fall97_101/Images/3_1/";

  // set the source for the images
  cartCoors.src = quadBase + "cartesian_coors.gif";
  quad1.src = quadBase + "quadrant1.gif";
  quad2.src = quadBase + "quadrant2.gif";
  quad3.src = quadBase + "quadrant3.gif";
  quad4.src = quadBase + "quadrant4.gif";

  homeBlk.src=base + "homeBlack.gif";
  homeBlu.src=base + "homeBlue.gif";
  homeRed.src=base + "homeRed.gif";

  chapBlk.src=base + "chapterBlack.gif";
  chapBlu.src=base + "chapterBlue.gif";
  chapRed.src=base + "chapterRed.gif";

  tutorBlk.src=base + "tutorialBlack.gif";
  tutorBlu.src=base + "tutorialBlue.gif";
  tutorRed.src=base + "tutorialRed.gif";

  hwrkBlk.src=base + "homeworkBlack.gif";
  hwrkBlu.src=base + "homeworkBlue.gif";
  hwrkRed.src=base + "homeworkRed.gif";

  syllBlk.src=base + "syllabusBlack.gif";
  syllBlu.src=base + "syllabusBlue.gif";
  syllRed.src=base + "syllabusRed.gif";

  gradBlk.src=base + "gradesBlack.gif";
  gradBlu.src=base + "gradesBlue.gif";
  gradRed.src=base + "gradesRed.gif";

} // end if navigator >= 3

// displays black as the off button color
function display_off( num ) {

  if (parseInt(navigator.appVersion.substring(0,1))>=3) {  //3.0 or greater.

     if   (num=="1") 
          document.images[0].src = homeBlk.src;
     else if (num=="2") 
          document.images[1].src = chapBlk.src;
     else if (num=="3") 
          document.images[2].src = tutorBlk.src;
     else if (num=="4") 
          document.images[3].src = hwrkBlk.src;
     else if (num=="5") 
          document.images[4].src = syllBlk.src;
     else if (num=="6") 
          document.images[5].src = gradBlk.src;
  
  }

} // end function display_off()

// displays red as the off button color (means we're on this page)
function display_off_page( num ) {

  if (parseInt(navigator.appVersion.substring(0,1))>=3) {  //3.0 or greater.

     if   (num=="1") 
          document.images[0].src = homeRed.src;
     else if (num=="2") 
          document.images[1].src = chapRed.src;
     else if (num=="3") 
          document.images[2].src = tutorRed.src;
     else if (num=="4") 
          document.images[3].src = hwrkRed.src;
     else if (num=="5") 
          document.images[4].src = syllRed.src;
     else if (num=="6") 
          document.images[5].src = gradRed.src;
  
  }

} // end function display_off_page()

function display_on( num ) {

  if (parseInt(navigator.appVersion.substring(0,1))>=3) {  //3.0 or greater.

    if   (num=="1")
         document.images[0].src = homeBlu.src;
    else if (num=="2") 
         document.images[1].src = chapBlu.src; 
    else if (num=="3") 
         document.images[2].src = tutorBlu.src; 
    else if (num=="4") 
         document.images[3].src = hwrkBlu.src; 
    else if (num=="5") 
         document.images[4].src = syllBlu.src; 
    else if (num=="6") 
         document.images[5].src = gradBlu.src; 

  } // end if navigator >= 3

} // end function display_on()

function setColor( color ) {

  if( color == "black" )
      document.bgColor = "black";
  else
      document.bgColor = "white";

}

// makes a window of width wth and height hgt with the document loaded in it
function makeWindow( document ) {
        base = "/~kentler/Fall97_101/";
     	indexWin=window.open( base + document + ".html", "indexWin",
                "toolbar=no,resizable=yes,scrollbars=yes,menubar=no,height=485,width=300");
     	indexWin.focus();
}

// makes a window of width wth and height hgt with the document loaded in it
function makePasswordWindow( document ) {
        base = "/~kentler/Fall97_101/";
        passWin=window.open( base + document + ".html", "passWin",
                "toolbar=no,resizable=yes,scrollbars=yes,menubar=no,height=300,width=485");
        passWin.focus();
}

// shows quandrants of the cartesian coordinate system
function showQuadrant( quadrant ) {

  if     ( quadrant == "0" )
         document.images[6].src = cartCoors.src; 
  else if( quadrant == "1" )
         document.images[6].src = quad1.src; 
  else if( quadrant == "2" )
         document.images[6].src = quad2.src; 
  else if( quadrant == "3" )
         document.images[6].src = quad3.src; 
  else if( quadrant == "4" )
         document.images[6].src = quad4.src; 

}