Initial revision

lang/cem/libcc.ansi/math/asin.c

@@ -0,0 +1,47 @@
+/*
+ * (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ *
+ * Author: Ceriel J.H. Jacobs
+ */
+/* $Header$ */
+
+#include	<errno.h>
+#include	<math.h>
+#include	"localmath.h"
+
+
+static double
+asin_acos(double x, int cosfl)
+{
+	int negative = x < 0;
+
+	if (negative) {
+		x = -x;
+	}
+	if (x > 1) {
+		errno = EDOM;
+		return 0;
+	}
+	if (x == 1) {
+		x = M_PI_2;
+	}
+	else x = atan(x/sqrt(1-x*x));
+	if (negative) x = -x;
+	if (cosfl) {
+		return M_PI_2 - x;
+	}
+	return x;
+}
+
+double
+asin(double x)
+{
+	return asin_acos(x, 0);
+}
+
+double
+acos(double x)
+{
+	return asin_acos(x, 1);
+}