functions:probability
syntax: NORMAL( x,a,b )
NORMAL returns the normal probability density
NORMAL(x,a,b) = exp( -0.5*((x-a)/b)^2 )/(b*sqrt(2*pi))
a is the mean of the distribution, and b is the standard
deviation, b must be >0.
syntax: FISHER( m,n,x )
FISHER returns Fisher's F-distribution with m and n degrees of
freedom, i.e., the probability FISHER(m,n,x) =
GAMMA((m+n)/2) / (GAMMA(m/2)*GAMMA(n/2)) *
integral from 0 to (m/n)*x of t^(m/2-1)/(t+1)^((m+n)/2) dt
The F-distribution is also known as the variance-ratio distribution
or Snedecor's distribution.
This function should be accurate to at least 0.001
for 1<=m<=60 and 1<=n<=30.
syntax: TINA( x,a,b,c )
TINA(x,a,b,c) = EXP((x-a)/c)*(1-ERF((x-a)/b)) / (2*c*EXP(b*b/(4*c*c)))
If (x-a)/b > 80 or (x-a)/c > 80, then TINA is set to zero. This was done
to circumvent floating overflow problems for large x.