From: Bill Joy <wnj@ucbvax.Berkeley.EDU>
Date: Sun, 3 Feb 1980 07:11:08 +0000 (-0800)
Subject: BSD 3 development
X-Git-Tag: BSD-3~36
X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/commitdiff_plain/b302fb5760d9701e0660ee0f18518ac5fca481db

BSD 3 development
Work on file usr/src/lib/libm/asin.c

Synthesized-from: 3bsd
---

diff --git a/usr/src/lib/libm/asin.c b/usr/src/lib/libm/asin.c
new file mode 100644
index 0000000000..cacb6b4fb1
--- /dev/null
+++ b/usr/src/lib/libm/asin.c
@@ -0,0 +1,48 @@
+/*
+	asin(arg) and acos(arg) return the arcsin, arccos,
+	respectively of their arguments.
+
+	Arctan is called after appropriate range reduction.
+*/
+
+#include	<errno.h>
+int errno;
+double atan();
+double sqrt();
+static double pio2	= 1.570796326794896619;
+
+double
+asin(arg) double arg; {
+
+	double sign, temp;
+
+	sign = 1.;
+	if(arg <0){
+		arg = -arg;
+		sign = -1.;
+	}
+
+	if(arg > 1.){
+		errno = EDOM;
+		return(0.);
+	}
+
+	temp = sqrt(1. - arg*arg);
+	if(arg > 0.7)
+		temp = pio2 - atan(temp/arg);
+	else
+		temp = atan(arg/temp);
+
+	return(sign*temp);
+}
+
+double
+acos(arg) double arg; {
+
+	if((arg > 1.) || (arg < -1.)){
+		errno = EDOM;
+		return(0.);
+	}
+
+	return(pio2 - asin(arg));
+}