ilogb() is a variant of logb(). Nearly the same replacement code as for logb().
Notable bugs fixed: The value for zero, infinite, or NaN arguments is broken on NetBSD, OpenBSD, and old AIX 5.1. 2012-04-03 Bruno Haible <br...@clisp.org> Tests for module 'ilogbl'. * modules/ilogbl-tests: New file. * tests/test-ilogbl.c: New file. New module 'ilogbl'. * lib/math.in.h (ilogbl): New declaration. * lib/ilogbl.c: New file. * m4/ilogbl.m4: New file. * m4/math_h.m4 (gl_MATH_H): Test whether ilogbl is declared. (gl_MATH_H_DEFAULTS): Initialize GNULIB_ILOGBL, HAVE_ILOGBL. * modules/math (Makefile.am): Substitute GNULIB_ILOGBL, HAVE_ILOGBL. Split sed invocation, to avoid the limit of 100 substitutions of HP-UX 'sed'. * modules/ilogbl: New file. * tests/test-math-c++.cc: Check the declaration of ilogbl. * doc/posix-functions/ilogbl.texi: Mention the new module. 2012-04-03 Bruno Haible <br...@clisp.org> Tests for module 'ilogbf'. * modules/ilogbf-tests: New file. * tests/test-ilogbf.c: New file. New module 'ilogbf'. * lib/math.in.h (ilogbf): New declaration. * lib/ilogbf.c: New file. * m4/ilogbf.m4: New file. * m4/math_h.m4 (gl_MATH_H): Test whether ilogbf is declared. (gl_MATH_H_DEFAULTS): Initialize GNULIB_ILOGBF, HAVE_ILOGBF, REPLACE_ILOGBF. * modules/math (Makefile.am): Substitute GNULIB_ILOGBF, HAVE_ILOGBF, REPLACE_ILOGBF. * modules/ilogbf: New file. * tests/test-math-c++.cc: Check the declaration of ilogbf. * doc/posix-functions/ilogbf.texi: Mention the new module. 2012-04-03 Bruno Haible <br...@clisp.org> Tests for module 'ilogb'. * modules/ilogb-tests: New file. * tests/test-ilogb.c: New file. * tests/test-ilogb.h: New file, based on tests/test-logb.h and tests/test-logb-ieee.h. New module 'ilogb'. * lib/math.in.h (ilogb): New declaration. * lib/ilogb.c: New file. * m4/ilogb.m4: New file. * m4/math_h.m4 (gl_MATH_H): Test whether ilogb is declared. (gl_MATH_H_DEFAULTS): Initialize GNULIB_ILOGB, HAVE_ILOGB, REPLACE_ILOGB. * modules/math (Makefile.am): Substitute GNULIB_ILOGB, HAVE_ILOGB, REPLACE_ILOGB. * modules/ilogb: New file. * tests/test-math-c++.cc: Check the declaration of ilogb. * doc/posix-functions/ilogb.texi: Mention the new module. 2012-04-03 Bruno Haible <br...@clisp.org> math: Provide FP_ILOGB0 and FP_ILOGBNAN. * lib/math.in.h (FP_ILOGB0, FP_ILOGBNAN): Define fallback. * tests/test-math.c: Check that FP_ILOGB0, FP_ILOGBNAN are defined. (main): Check their values. * doc/posix-headers/math.texi: Mention the FP_ILOGB0, FP_ILOGBNAN problem.