How to calculate T.INV() in c# without excel workbook. Is there any direct formula or class that can help me?.I have already Used "System.Web.UI.DataVisualization " name space but it is not...

public static double InverseTDistributionfun(int DF, double probability)
{
    double Tinv;
    try
    {
        chart.Charting.Chart objChart = new chart.Charting.Chart();
        Tinv = objChart.DataManipulator.Statistics.TDistribution(probability,DF, true);

        // value = c16 + dup * y30;

    }
    catch (Exception ex)
    {
        throw ex;
    }
    return Tinv;
}

[Microsoft.SqlServer.Server.SqlProcedure]
public static double SQLCLRCsharpSP(int DF, double probability)
{
    double _sum = 0.00;
    try
    {

        //if (type == "C")
        _sum = InverseTDistributionfun(DF, probability);
        //if (type == "A")
            //_sum = AlgTInvFun(probability, DF);
    }
    catch (Exception ex)
    {
        throw ex;
    }
    return  _sum;
}