The above equation is a normalized function, i.e., integration will give you 1.
So you can multiple it by any number.
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ok i understand normalized function http://mathworld.wolfram.com/NormalDistribution.html
ok i also understand the area under this normalized function is 1

but i am  puzzled by the missing r*r.

equation in your XML : fT = "h4/((Math.exp(cst/(r*T))-1)*(r*r*r))"

notice your XML : fT has only r*r*r but the equation on wikipedia has r*r*r*r*r

unless when normalized the r*r is absorbed? then it make sense to me now! I don't really know why now but at least i can accept the logic. (it that correct ?)......hahaha.