double invbinomial(double n,double k,double p)
{
if (k==0 && n>0 && p>=0 && p<=1)
return (1 - pow(p,1/n));
return invibeta(k+1,n-k,1-p);
}
double qt(double p, double df)
{
double t, invibeta();
t = invibeta(fabs(2*p-1), 0.5, df/2);
return((p>0.5?1:-1) * sqrt(t*df/(1-t)));
}
double invf(double df1, double df2, double f)
{
double x = invibeta(df2/2,df1/2,1-f);
return (x==0) ? 0 : df2*(1-x)/(df1*x);
}
