From be22b15ae2ff8d7fe06b6e14fddf0c5b444a95da Mon Sep 17 00:00:00 2001
From: rgrimes <rgrimes@FreeBSD.org>
Date: Fri, 27 May 1994 05:00:24 +0000
Subject: BSD 4.4 Lite Lib Sources

---
 lib/libm/common/tan.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 lib/libm/common/tan.c

(limited to 'lib/libm/common/tan.c')

diff --git a/lib/libm/common/tan.c b/lib/libm/common/tan.c
new file mode 100644
index 0000000..61ed5c5
--- /dev/null
+++ b/lib/libm/common/tan.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 1987, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)tan.c	8.1 (Berkeley) 6/4/93";
+#endif /* not lint */
+
+#include "trig.h"
+double
+tan(x) 
+double x;
+{
+	double a,z,ss,cc,c;
+	int k;
+
+	if(!finite(x))		/* tan(NaN) and tan(INF) must be NaN */
+		return x-x;
+	x = drem(x,PI);			/* reduce x into [-PI/2, PI/2] */
+	a = copysign(x,one);		/* ... = abs(x) */
+	if (a >= PIo4) {
+		k = 1;
+		x = copysign(PIo2-a,x);
+	}
+	else {
+		k = 0;
+		if (a < small) {
+			big+a;
+			return x;
+		}
+	}
+	z = x*x;
+	cc = cos__C(z);
+	ss = sin__S(z);
+	z *= half;			/* Next get c = cos(x) accurately */
+	c = (z >= thresh ? half-((z-half)-cc) : one-(z-cc));
+	if (k == 0)
+		return x+(x*(z-(cc-ss)))/c;	/* ... sin/cos */
+#ifdef national
+	else if (x == zero)
+		return copysign(fmax,x);	/* no inf on 32k */
+#endif	/* national */
+	else
+		return c/(x+x*ss);		/* ... cos/sin */
+}
-- 
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