{
	Normal Distribution Functions

		10/20/87

	Z(u)		- normal probability density function

	Q(u)		- Z(u) integrated from u to infinity

	u(p)		- u for known value p = Q(u)
}

NORMF : 1/sqrt(2*PI) ;

Z(u) = NORMF * exp(-u*u/2) ;

Q(u) = if( u, Q1(u), 1-Q1(-u) ) ;

Q1(u) = Z(u) * Q2(1/(1+.2316419*u)) ;

Q2(t) = t*(.31938153+t*(-.356563782+t*(1.781477937+
		t*(-1.821255978+t*1.330274429)))) ;

u(p) = if( .5-p, u1(p), -u1(1-p) ) ;

u1(p) = u2(sqrt(log(1/p/p))) ;

u2(t) = t - (2.515517+t*(.802853+t*.010328))/
		(1+t*(1.432788+t*(.189269+t*.001308))) ;