Returns the inverse of the standard normal cumulative distribution.

NORMSINV.mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
	<mx:Script>
		<![CDATA[
			
			
			private function inverseCumulativeNormalDistribution(v:Number):Number{
		
				//refer http://home.online.no/~pjacklam/notes/invnorm/ for how this works
			
				var a1:Number = -39.69683028665376;
				var a2:Number = 220.9460984245205;
				var a3:Number = -275.9285104469687;
				var a4:Number = 138.3577518672690;
				var a5:Number = -30.66479806614716;
				var a6:Number = 2.506628277459239;
				
				var b1:Number = -54.47609879822406;
				var b2:Number = 161.5858368580409;
				var b3:Number = -155.6989798598866;
				var b4:Number = 66.80131188771972;
				var b5:Number = -13.28068155288572;
			
				var c1:Number = -0.007784894002430293;
				var c2:Number = -0.3223964580411365;
				var c3:Number = -2.400758277161838;
				var c4:Number = -2.549732539343734;
				var c5:Number = 4.374664141464968;
				var c6:Number = 2.938163982698783;
			
				var d1:Number = 0.007784695709041462;
				var d2:Number = 0.3224671290700398;
				var d3:Number = 2.445134137142996;
				var d4:Number = 3.754408661907416;
				
				var p_low:Number = 0.02425;
				var p_high:Number = 1 - p_low;
				var q:Number = 0;
				var r:Number = 0;
				var result:Number = 0;
				
				//Rational approximation for lower region
				if((0 < v) &&  (v < p_low)){
					q = Math.sqrt( -2 * Math.log(v));
					result = (((((c1*q+c2)*q+c3)*q+c4)*q+c5)*q+c6) / ((((d1*q+d2)*q+d3)*q+d4)*q+1);
				//Rational approximation for central region
				}else{
					if((p_low <= arguments.v) && (v <= p_high )){
						q = v - 0.5;
						r = q*q;
						result = (((((a1*r+a2)*r+a3)*r+a4)*r+a5)*r+a6)*q / (((((b1*r+b2)*r+b3)*r+b4)*r+b5)*r+1);
						//Rational approximation for upper region
					}else{ 
						if((p_high < arguments.v) && (v < 1)){
							q = Math.sqrt(-2*Math.log(1-v));
							result = -(((((c1*q+c2)*q+c3)*q+c4)*q+c5)*q+c6) / ((((d1*q+d2)*q+d3)*q+d4)*q+1);
						}
					}
		        }
		       
		        
				return result;
			}
			
			private function startCalc():void{
				if(Number(input.text) < 1 && Number(input.text) > 0 ){
					invResult.text = inverseCumulativeNormalDistribution(Number(input.text)).toString();
				}
			}
		]]>
	</mx:Script>
	<mx:TextInput x="85" y="468" id="input"/>
	<mx:Button x="288" y="470" label="Calculate" click="startCalc()"/>
	<mx:Text x="371" y="470" text="" width="202" id="invResult"/>
	
	
	
</mx:Application>