1 files changed, 98 insertions, 0 deletions
diff --git a/libprakpp/include/prakcommon.hpp b/libprakpp/include/prakcommon.hpp
new file mode 100644
index 0000000..749d5ef
--- /dev/null
+++ b/libprakpp/include/prakcommon.hpp
@@ -0,0 +1,98 @@
+#pragma once
+
+#include <cmath>
+#include <functional>
+#include <vector>
+#include <iostream>
+
+#if defined(_MSC_VER) || !defined(__cpp_multidimensional_subscript) || __cplusplus < 202110L
+#warning "can not use multidimentional subscript operator: falling back to `operator()`"
+#undef MDSUBSCRIPT
+#else
+#define MDSUBSCRIPT
+#endif
+
+#ifdef NO_MDSUBSCRIPT
+#undef MDSUBSCRIPT
+#endif
+
+#ifdef MDSUBSCRIPT
+	#define SUBSCR_OPN [
+	#define SUBSCR_CLS ]
+	#define SUBSCR_OPRTR operator[]
+#else	
+	#define SUBSCR_OPN (
+	#define SUBSCR_CLS )
+	#define SUBSCR_OPRTR operator()
+#endif
+
+template <typename T>
+using function_t = std::function<T(const std::vector<T> &)>;
+
+namespace prak {
+
+/// stolen from [cppreference.com](https://en.cppreference.com/w/cpp/types/numeric_limits/epsilon)
+/// Compares 2 floating-point values up to `ulps` ULPS (units in the last place)
+template <class T>
+std::enable_if_t<not std::numeric_limits<T>::is_integer, bool>
+fequal(T x, T y, std::size_t ulps = 1)
+{
+    // Since `epsilon()` is the gap size (ULP, unit in the last place)
+    // of floating-point numbers in interval [1, 2), we can scale it to
+    // the gap size in interval [2^e, 2^{e+1}), where `e` is the exponent
+    // of `x` and `y`.
+ 
+    // If `x` and `y` have different gap sizes (which means they have
+    // different exponents), we take the smaller one. Taking the bigger
+    // one is also reasonable, I guess.
+    const T m = std::min(std::fabs(x), std::fabs(y));
+ 
+    // Subnormal numbers have fixed exponent, which is `min_exponent - 1`.
+    const int exp = m < std::numeric_limits<T>::min()
+                  ? std::numeric_limits<T>::min_exponent - 1
+                  : std::ilogb(m);
+ 
+    // We consider `x` and `y` equal if the difference between them is
+    // within `n` ULPs.
+    return std::fabs(x - y) <= ulps * std::ldexp(std::numeric_limits<T>::epsilon(), exp);
+}
+
+
+/// prints a vector
+template <typename T>
+void printv(const T &vec) {
+	std::cout << "std::vector { ";
+	for (const auto &x : vec) {
+		std::cout << x << ' ';
+	}
+	std::cout << '}' << std::endl;
+}
+
+/// An allocator that aligns memory to 64 bytes. Needed for AVX instructions.
+/// C++17 required for std::align_val_t 
+template <class T>
+struct align_alloc : public std::allocator<T> {
+	constexpr T* allocate( std::size_t n ) {
+		return static_cast<T*>(::operator new(sizeof (T) * n, std::align_val_t{64}));
+	}
+
+	constexpr void deallocate( T* p, std::size_t n ) {
+		::operator delete(p, std::align_val_t{64});
+	}
+};;
+
+/// alias prak::vector that is the same as std::vector, but uses aligned allocator 
+template <typename T>
+using vector = std::vector<T, align_alloc<T>>;
+
+/// prak value / pair value: a value with an error
+template <typename T>
+struct pvalue {	T val, err; };
+
+template <typename T>
+std::ostream &operator<<(std::ostream &os, const struct pvalue<T> &p) {
+	/* return os << "value {" << p.val << "±" << p.err << "}"; */
+	return os << p.val << "±" << p.err;
+}
+
+} // namespace prak