[comp.sys.ibm.pc.misc] acosh, asinh

asd1466@isc.rit.edu (A.S. Dumas) (02/11/91)

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.

Please email responses.

Thanks, Art
-- 
asd1466@ultb.isc.rit.edu

rickert@mp.cs.niu.edu (Neil Rickert) (02/14/91)

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