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MathGroup Archive 2012

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Function Exp[x^2]*Erfc[x]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125009] Function Exp[x^2]*Erfc[x]
  • From: Leslaw Bieniasz <nbbienia at cyf-kr.edu.pl>
  • Date: Fri, 17 Feb 2012 06:27:23 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com


Hi,

MATHEMATICA is supposed to contain all known rules from tables of 
functions etc. One of the very important special functions, related
to the function w(z) defined (for example) in Abramowitz and Stegun book,
is Exp[x^2]*Erfc[x]. Although it can be expressed formally as the product
of two other functions, Exp and Erfc, there is no effective way to compute
the values of the function in a wide range of x values, by using Exp and 
Erfc, because of the overflow in Exp[]. There are known approximations
to Exp[x^2]*Erfc[x] (for example ones produced by Cody and co-workers
a few decades ago), but I don't see any support for the function in 
MATHEMATICA. Is this indeed so, or I miss something?

Leslaw



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