Is it "n" or "pi" ?

[Adrian Spiridon]

Hello there,

        I want to calculate Bessel function of the second kind , Yn(z)  for n integer, using the formula : http://mathworld.wolfram.com/images/equations/BesselFunctionoftheSecondKind/NumberedEquation6.gif  from http://mathworld.wolfram.com/BesselFunctionoftheSecondKind.html .
        I am not sure, in the formula, whether it is power(z/2,-n) or power(z/2,-pi), Jn(z) or Jpi(z). Similar,on the last term : is it power(z/2,n) or power(z/2,pi) ?
        If I zoom the image, it seems to be pi, although n is probably correct.
 

PS:  I know Octave has this function built in, but I want to implement it myself.
       Also, where can I find the Octave source code of the function bessely ?


Thanx

Adrian