| 1 | /*
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| 2 | * Copyright (c) 2015 Jiri Svoboda
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup libmath
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| 30 | * @{
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| 31 | */
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| 32 | /** @file
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| 33 | */
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| 34 |
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| 35 | #include <asin.h>
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| 36 | #include <errno.h>
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| 37 | #include <math.h>
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| 38 |
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| 39 | /** Inverse sine (32-bit floating point)
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| 40 | *
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| 41 | * Compute inverse sine value.
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| 42 | *
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| 43 | * @param arg Inverse sine argument.
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| 44 | *
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| 45 | * @return Inverse sine value.
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| 46 | *
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| 47 | */
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| 48 | float32_t float32_asin(float32_t arg)
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| 49 | {
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| 50 | float32_t aval;
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| 51 |
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| 52 | if (arg < -1.0 || arg > 1.0) {
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| 53 | errno = EDOM;
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| 54 | return FLOAT32_NAN;
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| 55 | }
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| 56 |
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| 57 | aval = 2.0 * atan_f32(arg / (1.0 + sqrt_f32(1.0 - arg*arg)));
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| 58 | if (arg > 0.0)
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| 59 | return aval;
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| 60 | else
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| 61 | return -aval;
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| 62 | }
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| 63 |
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| 64 | /** Inverse sine (64-bit floating point)
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| 65 | *
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| 66 | * Compute inverse sine value.
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| 67 | *
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| 68 | * @param arg Inverse sine argument.
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| 69 | *
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| 70 | * @return Inverse sine value.
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| 71 | *
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| 72 | */
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| 73 | float64_t float64_asin(float64_t arg)
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| 74 | {
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| 75 | float64_t aval;
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| 76 |
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| 77 | if (arg < -1.0 || arg > 1.0) {
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| 78 | errno = EDOM;
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| 79 | return FLOAT64_NAN;
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| 80 | }
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| 81 |
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| 82 | aval = 2.0 * atan_f64(arg / (1.0 + sqrt_f64(1.0 - arg*arg)));
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| 83 | if (arg > 0.0)
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| 84 | return aval;
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| 85 | else
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| 86 | return -aval;
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| 87 | }
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| 88 |
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| 89 | /** @}
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| 90 | */
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