1 (in-package #:strictmath)
2 ; This file is taken from part of Evita Common Lisp.
4 ; Copyright (C) 1996-2007 by Project Vogue.
5 ; Written by Yoshifumi "VOGUE" INOUE. (yosi@msn.com)
7 ; Before that, it was based off of fdlibm
9 ; See fdlibm (http://www.netlib.org/fdlibm/)
10 ; See http://sources.redhat.com/newlib/
12 ; /* @(#)k_sin.c 5.1 93/09/24 */
14 ; * ====================================================
15 ; * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
17 ; * Developed at SunPro, a Sun Microsystems, Inc. business.
18 ; * Permission to use, copy, modify, and distribute this
19 ; * software is freely granted, provided that this notice
21 ; * ====================================================
24 ; /* __kernel_sin( x, y, iy)
25 ; * kernel sin function on [-pi/4, pi/4], pi/4 ~ 0.7854
26 ; * Input x is assumed to be bounded by ~pi/4 in magnitude.
27 ; * Input y is the tail of x.
28 ; * Input iy indicates whether y is 0. (if iy=0, y assume to be 0).
31 ; * 1. Since sin(-x) = -sin(x), we need only to consider positive x.
32 ; * 2. if x < 2^-27 (hx<#x3e400000 0), return x with inexact if x!=0.
33 ; * 3. sin(x) is approximated by a polynomial of degree 13 on
36 ; * sin(x) ~ x + S1*x + ... + S6*x
39 ; * |sin(x) 2 4 6 8 10 12 | -58
40 ; * |----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x +S6*x )| <= 2
43 ; * 4. sin(x+y) = sin(x) + sin'(x')*y
44 ; * ~ sin(x) + (1-x*x/2)*y
45 ; * For better accuracy, let
47 ; * r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6))))
49 ; * sin(x) = x + (S1*x + (x *(r-y/2)+y))
52 (defun float64-kernel-sin (x y iy)
53 (declare (values double-float))
54 (declare (type double-float x y))
55 (declare (type fixnum iy))
58 ((half #+nil 5.00000000000000000000e-01 #.(encode-float64 #x3FE00000 #x00000000))
59 (S1 #+nil -1.66666666666666324348e-01 #.(encode-float64 #xBFC55555 #x55555549))
60 (S2 #+nil 8.33333333332248946124e-03 #.(encode-float64 #x3F811111 #x1110F8A6))
61 (S3 #+nil -1.98412698298579493134e-04 #.(encode-float64 #xBF2A01A0 #x19C161D5))
62 (S4 #+nil 2.75573137070700676789e-06 #.(encode-float64 #x3EC71DE3 #x57B1FE7D))
63 (S5 #+nil -2.50507602534068634195e-08 #.(encode-float64 #xBE5AE5E6 #x8A2B9CEB))
64 (S6 #+nil 1.58969099521155010221e-10 #.(encode-float64 #x3DE5D93A #x5ACFD57C))
66 (hx (decode-float64 x)) ; high word of x
67 (ix (logand hx #x7fffffff)))
70 (when (< ix #x3e400000)
72 (when (eql (truncate x) 0) (return x)))
75 (r (+ s2 (* z (+ s3 (* z (+ s4 (* z (+ s5 (* z s6))))))))))
77 (return (+ x (* v (+ s1 (* z r)))))
78 (return (- x (- (- (* z (- (* half y) (* v r))) y) (* v s1))))))))