Execute Function in Calculated Field

I want to use a normsinv function within a calculated field, with the field calculated as:
NORMSINV(fieldname1/1000000)

The function I’d like to include is:

function NORMSINV(p)
{
// Coefficients in rational approximations
var a = new Array(-3.969683028665376e+01, 2.209460984245205e+02,
-2.759285104469687e+02, 1.383577518672690e+02,
-3.066479806614716e+01, 2.506628277459239e+00);

var b = new Array(-5.447609879822406e+01, 1.615858368580409e+02,
-1.556989798598866e+02, 6.680131188771972e+01,
-1.328068155288572e+01 );

var c = new Array(-7.784894002430293e-03, -3.223964580411365e-01,
-2.400758277161838e+00, -2.549732539343734e+00,
4.374664141464968e+00, 2.938163982698783e+00);

var d = new Array (7.784695709041462e-03, 3.224671290700398e-01,
2.445134137142996e+00, 3.754408661907416e+00);

// Define break-points.
var plow = 0.02425;
var phigh = 1 – plow;

// Rational approximation for lower region:
if ( p < plow ) {
var q = Math.sqrt(-2*Math.log(p));
return (((((c[0]*q+c[1])*q+c[2])*q+c[3])*q+c[4])*q+c[5]) /
((((d[0]*q+d[1])*q+d[2])*q+d[3])*q+1);
}

// Rational approximation for upper region:
if ( phigh < p ) {
var q = Math.sqrt(-2*Math.log(1-p));
return -(((((c[0]*q+c[1])*q+c[2])*q+c[3])*q+c[4])*q+c[5]) /
((((d[0]*q+d[1])*q+d[2])*q+d[3])*q+1);
}

// Rational approximation for central region:
var q = p – 0.5;
var r = q*q;
return (((((a[0]*r+a[1])*r+a[2])*r+a[3])*r+a[4])*r+a[5])*q /
(((((b[0]*r+b[1])*r+b[2])*r+b[3])*r+b[4])*r+1);
}

Is there a way I can execute this?

I am fine to include the function within my theme functions.php file, if that helps.

Thank you so much for your help in advance!