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extern/ustl/1.5/unumeric.h

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+// This file is part of the uSTL library, an STL implementation.
+//
+// Copyright (c) 2005 by Mike Sharov <msharov@users.sourceforge.net>
+// This file is free software, distributed under the MIT License.
+
+#ifndef UNUMERIC_H_6C99D6F6363832C644A6FFF336E84E18
+#define UNUMERIC_H_6C99D6F6363832C644A6FFF336E84E18
+
+namespace ustl {
+
+/// Returns the sum of all elements in [first, last) added to \p init.
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator, typename T>
+inline T accumulate (InputIterator first, InputIterator last, T init)
+{
+    while (first < last)
+	init += *first++;
+    return (init);
+}
+
+/// Returns the sum of all elements in [first, last) via \p op, added to \p init.
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator, typename T, typename BinaryFunction>
+inline T accumulate (InputIterator first, InputIterator last, T init, BinaryFunction binary_op)
+{
+    while (first < last)
+	init = binary_op (init, *first++);
+    return (init);
+}
+
+/// Assigns range [value, value + (last - first)) to [first, last)
+/// \ingroup NumericAlgorithms
+///
+template <typename ForwardIterator, typename T>
+inline void iota (ForwardIterator first, ForwardIterator last, T value)
+{
+    while (first < last)
+	*first++ = value++;
+}
+
+/// Returns the sum of products of respective elements in the given ranges.
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator1, typename InputIterator2, typename T>
+inline T inner_product (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, T init)
+{
+    while (first1 < last1)
+	init += *first1++ * *first2++;
+    return (init);
+}
+
+/// Returns the sum of products of respective elements in the given ranges.
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator1, typename InputIterator2, typename T,
+    	  typename BinaryOperation1, typename BinaryOperation2>
+inline T inner_product
+(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, T init,
+ BinaryOperation1 sumOp, BinaryOperation2 productOp)
+{
+    while (first1 < last1)
+	init = sumOp (init, productOp (*first1++, *first2++));
+    return (init);
+}
+
+/// Writes result such that result[i] = sum (first...first+i)
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator, typename OutputIterator>
+inline OutputIterator partial_sum (InputIterator first, InputIterator last, OutputIterator result)
+{
+    if (first < last)
+	*result = *first++;
+    while (first < last)
+	*++result = *first++ + *result;
+    return (result);
+}
+
+/// Writes result such that result[i] = sumOp (first...first+i)
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator, typename OutputIterator, typename BinaryOperation>
+inline OutputIterator partial_sum (InputIterator first, InputIterator last, OutputIterator result, BinaryOperation sumOp)
+{
+    if (first < last)
+	*result = *first++;
+    while (first < last)
+	*++result = sumOp (*first++, *result);
+    return (result);
+}
+
+/// Writes result such that result[i] = first[i] - first[i - 1]
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator, typename OutputIterator>
+inline OutputIterator adjacent_difference (InputIterator first, InputIterator last, OutputIterator result)
+{
+    if (first < last)
+	*result++ = *first++;
+    while (first < last)
+	*result++ = *first - *(first - 1);
+    return (result);
+}
+
+/// Writes result such that result[i] = differenceOp (first[i], first[i - 1])
+/// \ingroup NumericAlgorithms
+///
+template <typename InputIterator, typename OutputIterator, typename BinaryOperation>
+inline OutputIterator adjacent_difference (InputIterator first, InputIterator last, OutputIterator result, BinaryOperation differenceOp)
+{
+    if (first < last)
+	*result++ = *first++;
+    while (first < last)
+	*result++ = differenceOp (*first, *(first - 1));
+    return (result);
+}
+
+/// \brief Returns x^n.
+/// Donald Knuth's Russian Peasant algorithm.
+/// \ingroup NumericAlgorithms
+///
+template <typename T>
+inline T power (T x, unsigned n)
+{
+    T result (n % 2 ? x : 1);
+    while (n /= 2) {
+	x *= x;
+	if (n % 2)
+	    result *= x;
+    }
+    return (result);
+}
+
+/// \brief Returns x^n, using \p op instead of multiplication.
+/// Donald Knuth's Russian Peasant algorithm.
+/// \ingroup NumericAlgorithms
+///
+template <typename T, typename BinaryOperation>
+inline T power (T x, unsigned n, BinaryOperation op)
+{
+    T result (n % 2 ? x : 1);
+    while (n /= 2) {
+	x = op (x, x);
+	if (n % 2)
+	    result = op (result, x);
+    }
+    return (result);
+}
+
+} // namespace ustl
+
+#endif