function tensionCalcProcedure() {
  var unitWeight = parseFloat(document.tensionCalc.unitWeight.value);
  var scaleLength = parseFloat(document.tensionCalc.scaleLength.value);
  var toneIndex = parseInt(document.tensionCalc.tone.value);
  var tension = calculateTension(unitWeight, scaleLength, toneArray[toneIndex]).toFixed(1);
  document.tensionCalc.tensionDisplay.value = tension.toString();
  }