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diff --git a/vendor/libm-0.1.4/src/math/sin.rs b/vendor/libm-0.1.4/src/math/sin.rs
new file mode 100644
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+++ b/vendor/libm-0.1.4/src/math/sin.rs
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+// origin: FreeBSD /usr/src/lib/msun/src/s_sin.c */
+//
+// ====================================================
+// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+//
+// Developed at SunPro, a Sun Microsystems, Inc. business.
+// Permission to use, copy, modify, and distribute this
+// software is freely granted, provided that this notice
+// is preserved.
+// ====================================================
+
+use super::{k_cos, k_sin, rem_pio2};
+
+// sin(x)
+// Return sine function of x.
+//
+// kernel function:
+//      k_sin            ... sine function on [-pi/4,pi/4]
+//      k_cos            ... cose function on [-pi/4,pi/4]
+//      rem_pio2         ... argument reduction routine
+//
+// Method.
+//      Let S,C and T denote the sin, cos and tan respectively on
+//      [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
+//      in [-pi/4 , +pi/4], and let n = k mod 4.
+//      We have
+//
+//          n        sin(x)      cos(x)        tan(x)
+//     ----------------------------------------------------------
+//          0          S           C             T
+//          1          C          -S            -1/T
+//          2         -S          -C             T
+//          3         -C           S            -1/T
+//     ----------------------------------------------------------
+//
+// Special cases:
+//      Let trig be any of sin, cos, or tan.
+//      trig(+-INF)  is NaN, with signals;
+//      trig(NaN)    is that NaN;
+//
+// Accuracy:
+//      TRIG(x) returns trig(x) nearly rounded
+#[inline]
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn sin(x: f64) -> f64 {
+    let x1p120 = f64::from_bits(0x4770000000000000); // 0x1p120f === 2 ^ 120
+
+    /* High word of x. */
+    let ix = (f64::to_bits(x) >> 32) as u32 & 0x7fffffff;
+
+    /* |x| ~< pi/4 */
+    if ix <= 0x3fe921fb {
+        if ix < 0x3e500000 {
+            /* |x| < 2**-26 */
+            /* raise inexact if x != 0 and underflow if subnormal*/
+            if ix < 0x00100000 {
+                force_eval!(x / x1p120);
+            } else {
+                force_eval!(x + x1p120);
+            }
+            return x;
+        }
+        return k_sin(x, 0.0, 0);
+    }
+
+    /* sin(Inf or NaN) is NaN */
+    if ix >= 0x7ff00000 {
+        return x - x;
+    }
+
+    /* argument reduction needed */
+    let (n, y0, y1) = rem_pio2(x);
+    match n & 3 {
+        0 => k_sin(y0, y1, 1),
+        1 => k_cos(y0, y1),
+        2 => -k_sin(y0, y1, 1),
+        _ => -k_cos(y0, y1),
+    }
+}
+
+#[test]
+fn test_near_pi() {
+    let x = f64::from_bits(0x400921fb000FD5DD); // 3.141592026217707
+    let sx = f64::from_bits(0x3ea50d15ced1a4a2); // 6.273720864039205e-7
+    assert_eq!(sin(x), sx);
+}