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Diffstat (limited to 'nuttx/libc/math/lib_asinf.c')
-rw-r--r-- | nuttx/libc/math/lib_asinf.c | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/nuttx/libc/math/lib_asinf.c b/nuttx/libc/math/lib_asinf.c new file mode 100644 index 000000000..57e518acb --- /dev/null +++ b/nuttx/libc/math/lib_asinf.c @@ -0,0 +1,65 @@ +/************************************************************************ + * libc/math/lib_sinf.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) 2009-2011 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 asinf(float x) +{ + long double y, y_sin, y_cos; + + y = 0; + + while (1) + { + y_sin = sinf(y); + y_cos = cosf(y); + + if (y > M_PI_2 || y < -M_PI_2) + { + y = fmodf(y, M_PI); + } + + if (y_sin + FLT_EPSILON >= x && y_sin - FLT_EPSILON <= x) + { + break; + } + + y = y - (y_sin - x) / y_cos; + } + + return y; +} + |