| 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 <math.h>
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| 36 | #include <tanh.h>
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| 37 |
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| 38 | /** Hyperbolic tangent (32-bit floating point)
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| 39 | *
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| 40 | * Compute hyperbolic tangent value.
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| 41 | *
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| 42 | * @param arg Hyperbolic angle
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| 43 | *
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| 44 | * @return Hyperbolic tangent.
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| 45 | *
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| 46 | */
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| 47 | float32_t float32_tanh(float32_t arg)
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| 48 | {
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| 49 | float32_t em2x;
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| 50 |
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| 51 | if (arg > 9.0)
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| 52 | return 1.0;
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| 53 | if (arg < -9.0)
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| 54 | return -1.0;
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| 55 |
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| 56 | em2x = exp_f32(-2.0 * arg);
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| 57 | return (1.0 - em2x) / (1.0 + em2x);
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| 58 | }
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| 59 |
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| 60 | /** Hyperbolic tangent (64-bit floating point)
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| 61 | *
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| 62 | * Compute hyperbolic tangent value.
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| 63 | *
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| 64 | * @param arg Hyperbolic angle
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| 65 | *
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| 66 | * @return Hyperbolic tangent.
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| 67 | *
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| 68 | */
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| 69 | float64_t float64_tanh(float64_t arg)
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| 70 | {
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| 71 | float64_t em2x;
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| 72 |
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| 73 | if (arg > 19.0)
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| 74 | return 1.0;
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| 75 | if (arg < -19.0)
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| 76 | return -1.0;
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| 77 |
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| 78 | em2x = exp_f64(-2.0 * arg);
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| 79 | return (1.0 - em2x) / (1.0 + em2x);
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| 80 | }
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| 81 |
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| 82 | /** @}
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| 83 | */
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