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To: dj AT delorie DOT com
From: Nate Eldredge <nate AT cartsys DOT com>
Subject: Docs fixes for inverse trig functions.
Cc: djgpp-workers AT delorie DOT com
Date: Mon, 8 Jun 1998 17:09:00 -0700
Message-ID: <19980609000834.AAL6349@ppp100.cartsys.com>
Precedence: bulk

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The `atan2' function is rather sketchily documented, it doesn't mention that
it returns correct values for angles in the II and III quadrants. It took me
a long time to find a bug in one of my programs where I re-"corrected" this.
This fixes that, and also clarifies that inverse trig functions return
values in radians.

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*** src/libc/ansi/math/atan2.tx~	Mon Jul 10 05:39:32 1995
--- src/libc/ansi/math/atan2.txh	Mon Jun  8 17:01:20 1998
***************
*** 10,14 ****
  
  @subheading Return Value
  
! The arc tangent of @var{y/x}, with appropriate return values for
! @var{y}=0 or @var{x}=0.
--- 10,16 ----
  
  @subheading Return Value
  
! The arc tangent, in radians, of @var{y/x}, with appropriate return
! values for positive, negative, or zero values of @var{x}.
! E.g. @code{atan2(1, 0)} returns @var{PI/2}, and @code{atan2(0, -1)}
! returns @var{PI}.
*** src/libc/ansi/math/asin.tx~	Mon Jul 10 05:39:30 1995
--- src/libc/ansi/math/asin.txh	Mon Jun  8 17:03:14 1998
***************
*** 10,13 ****
  
  @subheading Return Value
  
! The arc sine of @var{x}.
--- 10,13 ----
  
  @subheading Return Value
  
! The arc sine, in radians, of @var{x}.
*** src/libc/ansi/math/acos.tx~	Mon Jul 10 05:39:30 1995
--- src/libc/ansi/math/acos.txh	Mon Jun  8 17:03:12 1998
***************
*** 10,13 ****
  
  @subheading Return Value
  
! The arc cosine of @var{x}.
--- 10,13 ----
  
  @subheading Return Value
  
! The arc cosine, in radians, of @var{x}.
*** src/libc/ansi/math/atan.tx~	Mon Jul 10 05:39:30 1995
--- src/libc/ansi/math/atan.txh	Mon Jun  8 17:03:12 1998
***************
*** 10,13 ****
  
  @subheading Return Value
  
! The arc tangent of @var{x}.
--- 10,13 ----
  
  @subheading Return Value
  
! The arc tangent, in radians, of @var{x}.

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Nate Eldredge
nate AT cartsys DOT com



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