ircd::math: Add fallback for vectorized hyperbolic tangent.

include/ircd/math/math.h

@@ -14,3 +14,10 @@
 #include "log2.h"
 #include "inv.h"
 #include "mean.h"
+#include "tanh.h"
+
+namespace ircd
+{
+	using math::mean;
+	using math::tanh;
+}

include/ircd/math/tanh.h

@@ -0,0 +1,29 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2021 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_MATH_TANH_H
+
+namespace ircd::math
+{
+	template<class T>
+	typename std::enable_if<simd::is<T>(), T>::type
+	tanh(T);
+}
+
+template<class T>
+inline typename std::enable_if<ircd::simd::is<T>(), T>::type
+ircd::math::tanh(T a)
+{
+	for(uint i(0); i < simd::lanes<T>(); ++i)
+		a[i] = std::tanh(a[i]);
+
+	return a;
+}