[Proj] Geo Transfoms and calculations

Gerald I. Evenden geraldi.evenden at gmail.com
Tue Dec 30 13:24:05 EST 2008

On Tuesday 30 December 2008 12:39:57 pm Eric Miller wrote:
> You need only a minor modification to Gerald's libproj4 to compile on
> windows.  Because Microsoft is lame, their math library does not include
> atanh (or asinh or acosh).

That's incredible!  H&S indicate these are C99 so that may be part of the 
reason.  But still ... it is almost 09.  It just shows that nobody in Redmond 
got beyond 4th grade math ... oops, arithmatic.

> Previously, I overcame this by building in a naive implementation of
> atanh as:
> double atanh( double x )
> {
> 	return log((1 + x)/(1 - x))/2;
> }
> Since Gerald has since embraced the GSL, maybe we can get him to use
> the GSL versions of those functions and let the GNU folks handle
> platform compatibility.

I use MIT which is apparently tolerated by GSL but I don't want to get into 
that can of ugly  worms.  Besides, I do not have the libm source anyway.  
Kinda brings up a point: isn't gcc and library under GSL so that nobody can 
distribute a binary that uses the library without the associated BS?

All of the equivalent forms, like above, ought to be available in math 
references on the Internet (just google 'atanh') or in Abramowitz(sp.).
Put the code into gatesmath.c and gatesmath.h and attach to the Makefile 
lists.  ;-) NO, NO! Don't answer that!  No more discussion on this subject!

I'm sorry, but it is crap like that that makes me have such a loathesome 
opinion of M$.
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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