Eggleton IMF in amuse ?

[teuben]

One of my users in NEMO was noticing that in Aarseth's NBODY4 code a possibly minor typo slipped in, as explainted in their PR:

teuben/nemo#181

I don't have access to the quoted book, but in section 1.6 Eggletons IMF (is this used anywhere in AMUSE?) is
0.3 (u / (1-u))**0.5 instead of 0.3 u / (1-u)**0.5 used in Sverre's code.

Any opinions on this?

[stevemcmillan]

I don’t think this formula is used in AMUSE, but this looks like a very easy mistake to make when coding an expression. Stephen L. W. McMillan Emeritus Professor of Physics, Drexel University

[teuben]

For me it's still between Sverre and Peter.... so we need another reference where Peter published this perhaps?

Not knowing how many have used this IMF in nbody4, another option could be to allow both by extending Sverre's KZ(20), so it's "backwards" compatible.

[stevemcmillan]

There were only 20 in NBODY4? I think by NBODY5 it went up to 50. But I’m not sure that adding an option to support an incorrect formula is a great idea. Stephen L. W. McMillan Emeritus Professor of Physics, Drexel University

[teuben]

my version of nbody4 (which is from Sverre's website) counts to KZ(40).

I also just noted sverre was using ZM = 0.3D0*XX/(1.D0 - XX)**0.55, note the power 0.55, whereas 0.5 was claimed. I don't have the book and our library doesn't seem to have it.

[teuben]

so probing the community again, i still am unclear if I should Eggleton's book or Aarseth's code. Given I don't have access to E's book, I'm leaving this open.