logl() is missing from Cygwin's stdlib

[b-k]

Need to add logl to AC_CHECK_FUNCS in configure.ac.

Can add logl.m4 to provide if missing.
http://git.savannah.gnu.org/cgit/gnulib.git/tree/m4/logl.m4

[jgmbenoit]

Or add gnulib support for asprintf, logl, and the coming ones.

[iantist]

As someone who's trying to learn C and Linux in part from your book, this is a bit confusing. Editing configure.ac was no problem but I'm not sure how to add logl.m4. Any help would be greatly appreciated.

[jgmbenoit]

You cannot add logl.m4 like that: logl.m4 is part of gnulib [1]:
gnulib support may be added.

[1] https://www.gnu.org/software/gnulib/

[jgmbenoit]

An other possibility, is to add by hand logl as asprintf was added: if you are not familiar with GNULib which is not that well documented, this is certainly the best way to proceed.