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From: rickert@mp.cs.niu.edu (Neil Rickert)
Newsgroups: sci.math,comp.sys.ibm.pc.misc
Subject: Re: acosh, asinh
Message-ID: <1991Feb14.152807.18420@mp.cs.niu.edu>
Date: 14 Feb 91 15:28:07 GMT
References: <1991Feb11.144748.3273@isc.rit.edu>
Organization: Northern Illinois University
Lines: 18

In article <1991Feb11.144748.3273@isc.rit.edu> asd1466@isc.rit.edu (A.S. Dumas) writes:
>
>Has anyone written functions to do inverse hyperbolic sine and cosine
>(or know a math function that could be implemented)?
>I know that x=ln(2*u) gives a good approximation for x > 10 degrees or so
>but I need a function for much smaller values of x.

 RTFM.  Or should that be RTFT where the second T stands for Textbook.

 There are standard well known formulae:  x=ln(u+sqrt(u^2-1)) is the one
for inverse cosh.  If your calculus text doesn't give these, find a decent
text.

-- 
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  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115                                   +1-815-753-6940