diff options
Diffstat (limited to 'nuttx/libc/math/lib_logf.c')
-rw-r--r-- | nuttx/libc/math/lib_logf.c | 77 |
1 files changed, 0 insertions, 77 deletions
diff --git a/nuttx/libc/math/lib_logf.c b/nuttx/libc/math/lib_logf.c deleted file mode 100644 index 3815fef84..000000000 --- a/nuttx/libc/math/lib_logf.c +++ /dev/null @@ -1,77 +0,0 @@ -/************************************************************************ - * libc/math/lib_logf.c - * - * This file is a part of NuttX: - * - * Copyright (C) 2012 Gregory Nutt. All rights reserved. - * Ported by: Darcy Gong - * - * It derives from the Rhombs OS math library by Nick Johnson which has - * a compatibile, MIT-style license: - * - * Copyright (C) 2009, 2010 Nick Johnson <nickbjohnson4224 at gmail.com> - * - * Permission to use, copy, modify, and distribute this software for any - * purpose with or without fee is hereby granted, provided that the above - * copyright notice and this permission notice appear in all copies. - * - * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES - * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR - * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES - * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN - * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF - * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. - * - ************************************************************************/ - -/************************************************************************ - * Included Files - ************************************************************************/ - -#include <math.h> -#include <float.h> - -/************************************************************************ - * Public Functions - ************************************************************************/ - -float logf(float x) -{ - float y, y_old, ey, epsilon; - - y = 0.0; - y_old = 1.0; - epsilon = FLT_EPSILON; - - while (y > y_old + epsilon || y < y_old - epsilon) - { - y_old = y; - ey = exp(y); - y -= (ey - x) / ey; - - if (y > 700.0) - { - y = 700.0; - } - - if (y < -700.0) - { - y = -700.0; - } - - epsilon = (fabs(y) > 1.0) ? fabs(y) * FLT_EPSILON : FLT_EPSILON; - } - - if (y == 700.0) - { - return INFINITY; - } - - if (y == -700.0) - { - return INFINITY; - } - - return y; -} |