Initial revision

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

@@ -0,0 +1,35 @@
+/*
+ * (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>
+
+double
+pow(double x, double y)
+{
+	double dummy;
+
+	if ((x == 0 && y == 0) ||
+	    (x < 0 && modf(y, &dummy) != 0)) {
+		errno = EDOM;
+		return 0;
+	}
+
+	if (x == 0) return x;
+
+	if (x < 0) {
+		double val = exp(log(-x) * y);
+		if (modf(y/2.0, &dummy) != 0) {
+			/* y was odd */
+			val = - val;
+		}
+		return val;
+	}
+
+	return exp(log(x) * y);
+}