interpolation

by davidjb95

HTML

<input type="textbox" id="timeNum" Value="2.2" />
<input type="button" id="AddLink" value="Find Value" onClick="interpolation();" />
Amount of rainfall at time: <p id='output'></p>

JavaScript

var rainfall = [0.00, 0.04, 0.11, 0.6, 0.87, 0.95, 1.00];
function interpolation(){
	var time = document.getElementById("timeNum").value;
  var floor = (Math.floor(time));
  var ceil = (Math.ceil(time));
  var finalValue = rainfall[floor] + (rainfall[ceil] - rainfall[floor])*((time - floor)/(ceil - floor));
  var finalValueFloat = finalValue.toFixed(2);
  document.getElementById("output").innerHTML = finalValueFloat;
}