#401 describe(psi); claims Maxima can't evaluate psi

closed
nobody
5
2006-03-27
2003-09-18
Robert Dodier
No

describe(psi); claims that Maxima can't evaluate the
psi (the logarithmic derivative of gamma). Indeed
psi[n](x); returns a simple expression involving
zeta(n+1) for integer arguments x, and just psi[n](x)
for other arguments.

But there is another implementation of psi in the bffac
module, so load(bffac); bpsi(n, x, precision); does
yield numerical results for general arguments.

It seems like the right thing to do is to have psi call
bfpsi for arguments it can't evaluate.

Another slightly less right thing is to change the
description of psi to say that bfpsi in bffac can
handle general arguments.

For what it's worth,
Robert Dodier

Discussion

  • Robert Dodier
    Robert Dodier
    2004-10-10

    • labels: --> Documentation
     
  • Robert Dodier
    Robert Dodier
    2006-03-27

    Logged In: YES
    user_id=501686

    Documentation for psi was changed at some point to mention
    bfpsi in connection with numerical values. Closing this
    report as fixed.

     
  • Robert Dodier
    Robert Dodier
    2006-03-27

    • status: open --> closed