Using a Statistical Formula in AS3

[saratogacoach]

Hi,

I am working on an eLearning lesson that needs to score quiz results using a statistical formula called a probit function.

There are formulas in many languages (VB, C++, etc.) for the probit function, but not in AS3. The closest I can find is in JavaScript.

Other languages:

http://home.online.no/~pjacklam/notes/invnorm/

JavaScript:

http://home.online.no/~pjacklam/notes/invnorm/impl/misra/normsinv.html

I wonder if this JavaScript version can serve as the basis for an AS3 version of the formula?

Any help would be appreciated.

Kind Regards,

[Guest]

What is the problem? From a quick look, the JS one should translate nearly perfect to AS3.

[kglad]

it needs almost no editing except to rid the duplicate variable declarations.  and, at most:

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

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

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

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

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

    // Rational approximation for lower region:
    if (p<plow) {
        var q:Number=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) {
        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:
    q=p-0.5;
    var r:Number=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);
}

[saratogacoach]

Hi,

Thanks for your help. I'll set up a new Fla using AS3. This was the "big" formula, but there are a few other math operation (+, -, *, /) some if/esle conditionals. I'll try to figure out how use the 4 score variables from the quiz and run the formulas to get the end results. (As mentioned, I already have done this in JS, even some AS2, in an other authoring software, but my AS3 skills are far more limited.)

Again, thanks for your help.

Kind Regards,

[kglad]

you're welcome.

as dave mentioned, you can copy just about any javascript into an as3 file, correct the few compiler errors that result from sloppy javascript coding and execute error-free actionscript.

[saratogacoach]

Hi,

Thanks for explaining this.

My bigger challenge maybe getting all the maths to work, plugging in the variables from the other swf's SO (separate thread: http://forums.adobe.com/message/3601240#3601240).

Kind Regards,

[kglad · Accepted solution]

i see rr is helping you in that linked thread.   he's knowledgable so follow his suggestions.

[saratogacoach]

Hi,

Thanks. Yes, getting help there and making progress.

Kind Regards,

[kglad]

you're welcome.