FY(y)=2Φ(√(y-1))-2Φ(0)fY(y)=FY'(y)=2Φ'(√(y-1))*1/(2√(y-1))=2/√(2π)*e^[-(y-1)/2]*1/(2√(y-1))=1/√[2π(y-1)]*e^[-(y-1)/2]*
