Add approximation functions

Author: stijnh

include/kernel_float.h

@@ -1,6 +1,7 @@
 #ifndef KERNEL_FLOAT_H
 #define KERNEL_FLOAT_H
 
+#include "kernel_float/approx.h"
 #include "kernel_float/base.h"
 #include "kernel_float/bf16.h"
 #include "kernel_float/binops.h"

include/kernel_float/apply.h

@@ -130,6 +130,9 @@ struct apply_impl {
 
 template<typename F, size_t N, typename Output, typename... Args>
 struct apply_fastmath_impl: apply_impl<F, N, Output, Args...> {};
+
+template<int Deg, typename F, size_t N, typename Output, typename... Args>
+struct apply_approx_impl: apply_fastmath_impl<F, N, Output, Args...> {};
 }  // namespace detail
 
 struct accurate_policy {
@@ -142,6 +145,14 @@ struct fast_policy {
     using type = detail::apply_fastmath_impl<F, N, Output, Args...>;
 };
 
+template<int Degree = -1>
+struct approximate_policy {
+    template<typename F, size_t N, typename Output, typename... Args>
+    using type = detail::apply_approx_impl<Degree, F, N, Output, Args...>;
+};
+
+using default_approximate_policy = approximate_policy<>;
+
 #ifdef KERNEL_FLOAT_POLICY
 using default_policy = KERNEL_FLOAT_POLICY;
 #else