Import sources from 2011-03-30 iso image

1 files changed, 24 insertions, 0 deletions

diff --git a/sys/src/ape/lib/ap/math/tanh.c b/sys/src/ape/lib/ap/math/tanh.c
new file mode 100755
index 000000000..cad68362b
--- /dev/null
+++ b/sys/src/ape/lib/ap/math/tanh.c
@@ -0,0 +1,24 @@
+#include <math.h>
+
+/*
+	tanh(arg) computes the hyperbolic tangent of its floating
+	point argument.
+
+	sinh and cosh are called except for large arguments, which
+	would cause overflow improperly.
+ */
+
+double
+tanh(double arg)
+{
+
+	if(arg < 0) {
+		arg = -arg;
+		if(arg > 21)
+			return -1;
+		return -sinh(arg)/cosh(arg);
+	}
+	if(arg > 21)
+		return 1;
+	return sinh(arg)/cosh(arg);
+}