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MathGroup Archive 2004

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(N)Integrate help - convergence problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48694] (N)Integrate help - convergence problem
  • From: Patrick Jemmer <patrick.jemmer at unn.ac.uk>
  • Date: Thu, 10 Jun 2004 02:44:40 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

I am trying to do integrals such as the ones below, but am getting error
messgaes.. can anyone help me out please?

"NIntegrate :: ncvb : NIntegrate failed to converge to prescribed accuracy
after 7 recursivebisections in r near r = 4.22449...."
 
The outputs are as follows

  0.531684
 -0.993442
 -0.461758
 -0.0316842
 -0.00655776
 -0.038242

but are I guess nonsense, as they are non-converged.


I'd be happy to use either Integrate or NIntegrate: whichever works!




Many thanks, Patrick.

---------------------------------------------------


(* KINETIC & POTENTIAL OPERATORS *)

T[x_]:=(1/r^2)*D[  r^2*D[x, r], r ];

V := -1/r;

(*  WAVEFUNCTION *)

Fit5g = 

Sqrt[
0.0711280497855832 / E^(16*r^2) + 
0.0950242005793304 / E^(4*r^2) + 
0.09001525518121072 / E^r^2 + 
0.011332742959622262 / E^(r^2/4) - 
0.0003397835348217242 / E^(r^2/16)
];

(* CALCULATE ENERGIES *)

TT5 = -(1/2)*Fit5g*T[Fit5g]//Simplify;

VV5 = Fit5g*V*Fit5g //Simplify;

KK5 = TT5 + VV5//Simplify;

TTT5 = 4*Pi*r^2*TT5//Simplify;

VVV5 = 4*Pi*r^2*VV5 //Simplify;

KKK5 = TTT5+ VVV5//Simplify;

TE5 = NIntegrate[ TTT5, {r, 0, Infinity} ]

VE5 = NIntegrate[ VVV5, {r, 0, Infinity} ]

EE5 = TE5 + VE5 //Simplify


--------------------------------------------------------------------
Eur Chem Dr  Patrick Jemmer
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MRSC MInstP MIMA CChem CPhys CMath  
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----------------------------------------
Siihr u Frith sil; sy m'ture'sw fisol. Hy'l, Frith na'f eloyhimint,
vappilimint'f flis : "Hlooza u Azla ye'' hririn sihn.Thanif sonni sy
m'hreth." Ky' silla Frith fy m'las eloyhim flisla rui'.
For God is good; he gives us light. And came they to Frith, calling unto
him: "There is no life because the Lord is dead. We are doomed." For Frith
it was that came down from the sky.



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