* gsl-1.2
@ 2002-11-03 7:17 Alexander Babansky
2002-11-03 22:11 ` gsl-1.2 Brian Gough
0 siblings, 1 reply; 2+ messages in thread
From: Alexander Babansky @ 2002-11-03 7:17 UTC (permalink / raw)
To: gsl-discuss
Hi,
I've found a small bug in Ei(x) function Reference manual(section
Exponential Integral)
In definition of Ei(x) it should be:
Ei(x) := - PV(\int_{-x}^\infty dt \exp(-t)/t)
(with "-" sign).
True mathematical definition of Ei(x) is:
Ei(x) := PV(\int_{-infinity}^x dt \exp(t)/t
When you change varibles, x-> -x you will get that "-" sign.
Bug is only in Reference manual not in Ei(x) itself.
Sincerely,
Alex
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: gsl-1.2
2002-11-03 7:17 gsl-1.2 Alexander Babansky
@ 2002-11-03 22:11 ` Brian Gough
0 siblings, 0 replies; 2+ messages in thread
From: Brian Gough @ 2002-11-03 22:11 UTC (permalink / raw)
To: Alexander Babansky; +Cc: gsl-discuss
Alexander Babansky writes:
> Hi, I've found a small bug in Ei(x) function Reference
> manual(section Exponential Integral) In definition of Ei(x) it
> should be: Ei(x) := - PV(\int_{-x}^\infty dt \exp(-t)/t) (with "-"
> sign).
> True mathematical definition of Ei(x) is: Ei(x) :=
> PV(\int_{-infinity}^x dt \exp(t)/t When you change varibles, x-> -x
> you will get that "-" sign. Bug is only in Reference manual not in
> Ei(x) itself.
Thanks, I'll correct it.
regards
Brian Gough
^ permalink raw reply [flat|nested] 2+ messages in thread
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