musl - cacosh.c - Comment needs correction

Date: Fri, 8 Mar 2024 15:20:09 +1100 (AEDT)
From: Damian McGuckin <damianm@....com.au>
To: MUSL <musl@...ts.openwall.com>
Subject: cacosh.c - Comment needs correction


The routine produces the correct answer.

However, currently, the comment at the top says

 	/* acosh(z) = i acos(z) */

I believe this is technically wrong;

To reflect the code, it should be changed to something like:

 	/* cacosh(z) = acosh(x +/- i y) = +/- i acos(x + i y) */

Somebody may want to rephrase that, i.e. if the sign of 'y' is positive
then the result is

 	i * cacos(z)

If the sign is negative, then the result is

 	-i * cacos(z)

I could always be wrong - Damian

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