Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2003
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Re: Re: Trouble with Integrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39370] Re: [mg39316] Re: [mg39268] Re: [mg39264] Trouble with Integrate
  • From: Vladimir Bondarenko <vvb at mail.strace.net>
  • Date: Thu, 13 Feb 2003 04:51:59 -0500 (EST)
  • References: <200302070807.DAA26439@smc.vnet.net> <200302110941.EAA26028@smc.vnet.net>
  • Reply-to: Vladimir Bondarenko <vvb at mail.strace.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Marko Vojinovic <vojinovi at panet.co.yu> wrote on Tue, 11 Feb 2003 04:41:28

MV> Let

MV> g = Sqrt[1+x^(2a)]-x^a

MV> where if we put the parameter a to be 2 we recover the original function, f.
MV> Now,

MV> Integrate[g,{x,0,Infinity}] /. a->2

MV> gives the correct answer


In[1] := Integrate[Sqrt[1 + x^(2a)] - x^a, {x, 0, Infinity}] /. a -> 2/3

Out[1] = -(Gamma[-5/4]*Gamma[7/4])/(2*Sqrt[Pi])   (*  <- INVALID  *)

In[2] := N[%]

Out[2] = -1.01666


Actually this integral, obviously, diverges to the plus infinity.

In[3] := N[Integrate[Sqrt[1 + x^(2a)] - x^a, {x, 0, 10^10}] /. a -> 2/3]

Out[3] = 3232.


Best wishes,

Vladimir Bondarenko
Mathematical and Production Director
Symbolic Testing Group

Web  :  Self-censorship: Steve will edit it out all the same ;-)
        http://www.CAS-testing.org/  GEMM Project            (95% ready)
        
Email:  vvb at mail.strace.net
Voice:  (380)-652-447325 Mon-Fri 6 a.m. - 3 p.m. GMT
ICQ  :  173050619
Mail :  76 Zalesskaya Str, Simferopol, Crimea, Ukraine




  • Prev by Date: Re: Algebra of differential operators
  • Next by Date: Simple List question. HELP.
  • Previous by thread: Re: Re: Trouble with Integrate
  • Next by thread: Re: Trouble with Integrate