Olivier Ramare on Mon, 30 Jun 2003 11:45:35 +0200 |
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ln gamma |
Dear all, Trying to understand the code of PARI that computes lngamma for complex argument: cxlngamma. The trouble is that the answer has an argument between -pi and pi and that I would rather it to be the continuous branch that has 0 imaginary part on the real axis. This code is a bit difficult to read (no comments, variables like p1, p2 ...) and I don't even see which formula is being used, because the initialisation of the variables is fairly ... intricate (half of the code if I understand well). Among the things I don't grasp: -- lines like "pitemp = mppi(l2); setexpo(pitemp,2); " "p7 = mplog(pitemp); setexpo(pitemp,1);" "setexpo(p7,-1); " What can be this setexpo-way of doing ?? -- What about the length in this ? "p5=cgetg(3,t_COMPLEX);" "p5[1]=lgetr(l2); setlg(p5[1],4);" "p5[2]=lgetr(l2); setlg(p5[2],4);" -- who knows who is bernzone ? Well, any comments on this piece of code would be appreciated, I'm fairly drowned in it :((( Best, Amities, Olivier