question: where can i find the equations to verify the calculations used? like wikipedia or other physics sources.

known/discovered analyzing your codes:
h = PLANCK = 6.6252 E-34
h4 = 4.*h*1.e47     = 2.65008.e14                                           [color=red]  // what is this?[/color]
c =the speed of light = 299 792 458 m / s
k =Boltzman k, 1.38E-23 J/K
cst = h*c/(k*1.e-10)  = 1.43.e8                                            [color=red] // // what is this constant?[/color]
fT = "h4/((Math.exp(cst/(r*T))-1)*(r*r*r))"

what i am trying to do.
change the lamda to nanometre nm instead of 1 Ångström ? 1×10-10 metre

i am guessing i need to change h4 = 4.*h*1.e4[b][color=blue]6[/color][/b]  for the nanometer calculation, i am guessing your calculation are for Ångström metre.

am i correct?

some references i look at.