samer@4: function y=erfp(x)
samer@4: % erfp - returns Pr(X>x) for a normalised Gaussian random variable
samer@4: %
samer@4: % erfp :: X:real -> Z:real.
samer@4: %
samer@4: % Y = integeral from X to infinity of 
samer@4: % (1/sqrt(2*pi)) * exp(-0.5*t.^2)
samer@4: 
samer@4: y = erfc(x/sqrt(2))/2;