var nseg=document.survey.nseg.selectedIndex+2;
document.survey.iseg.value=1;
var iseg=0;
var snone=0;
var dd = new Array();
var ss = new Array();
var hh = new Array();
for (var i=0; i<nseg; i++) {
  dd[i]=snone;
  ss[i]=snone;
  hh[i]=snone;
}
document.survey.dist.value=snone;
document.survey.slop.value=snone;
document.survey.hdng.value=snone;
showlog();

function showlog() {
  document.survey.surveylog.text="";
  var st="Section   Distance  Slope     Heading\n";
  var xx=0;
  var yy="";
  for (var i=0; i<nseg; i++) {
    xx=i+1;
    yy=n2s(xx);
    st=st+yy;
    xx=dd[i];
    yy=n2s(xx);
    st=st+yy;
    xx=ss[i];
    yy=n2s(xx);
    st=st+yy;
    xx=hh[i];
    yy=n2s(xx);
    st=st+yy+"\n";
  }
  document.survey.surveylog.value=st;
}

function n2s(x) {
  var sxx=String(x);
  var len=sxx.length;
  if (len < 10) {
    while (len < 10) {
      sxx=sxx+" ";
      len=sxx.length;
    }
  }
  return sxx;
}
function savseg() {
  var i1 = parseFloat(document.survey.iseg.value);
  var i2 = parseFloat(document.survey.dist.value);
  var i3 = parseFloat(document.survey.slop.value);
  var i4 = parseFloat(document.survey.hdng.value);
  if (!isNaN(i1) && !isNaN(i2) && !isNaN(i3) && !isNaN(i4)) {
    dd[i1-1] = i2;
    ss[i1-1] = i3;
    hh[i1-1] = i4;
    if (i1 >= nseg) {i1=1;} 
    document.survey.iseg.value=i1+1;
    document.survey.dist.value=dd[i1];
    document.survey.slop.value=ss[i1];
    document.survey.hdng.value=hh[i1];
    showlog();
    }
  else {
    if (isNaN(i1)) {document.survey.iseg.value="Error";}
    if (isNaN(i2)) {document.survey.dist.value="Error";}
    if (isNaN(i3)) {document.survey.slop.value="Error";}
    if (isNaN(i4)) {document.survey.hdng.value="Error";}
  }
}
function nxtseg() {
  nseg=document.survey.nseg.selectedIndex+2;
  iseg=document.survey.iseg.value-1;
  iseg = ((iseg+1) % nseg);
  document.survey.iseg.value=iseg+1;
  document.survey.dist.value=dd[iseg];
  document.survey.slop.value=ss[iseg];
  document.survey.hdng.value=hh[iseg];
}
function tstloop() {
  var xx = 0.0;
  var yy = 0.0;
  var dsum = 0.0;
  for (var ii=0; ii<nseg; ii++) {
    xx = xx + dd[ii]*Math.cos(ss[ii]*Math.PI/180.0)*Math.sin(hh[ii]*Math.PI/180.0);
    yy = yy + dd[ii]*Math.cos(ss[ii]*Math.PI/180.0)*Math.cos(hh[ii]*Math.PI/180.0);
    dsum = dsum + dd[ii]*Math.cos(ss[ii]*Math.PI/180.0);
    }
  xx = 100.0*Math.pow(xx*xx+yy*yy,0.5)/dsum;
  document.survey.pcnt.value=100.0-xx;
}
function rdnseg() {
  var xx=0;
  nseg = document.survey.nseg.selectedIndex+2;
  for (var i=0; i<nseg; i++) {
      xx=dd[i];
      if (isNaN(xx)) {dd[i]=snone;}
      xx=ss[i];
      if (isNaN(xx)) {ss[i]=snone;}
      xx=hh[i];
      if (isNaN(xx)) {hh[i]=snone;}
  }
  showlog();
  document.survey.iseg.value=1;
  document.survey.dist.value=dd[0];
  document.survey.slop.value=ss[0];
  document.survey.hdng.value=hh[0];
}