29 Numerics library [numerics]

29.8 Generalized numeric operations [numeric.ops]

29.8.6 Partial sum [partial.sum]

template <class InputIterator, class OutputIterator> OutputIterator partial_sum( InputIterator first, InputIterator last, OutputIterator result); template <class InputIterator, class OutputIterator, class BinaryOperation> OutputIterator partial_sum( InputIterator first, InputIterator last, OutputIterator result, BinaryOperation binary_op);

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Requires: InputIterator's value type shall be constructible from the type of *first. The result of the expression acc + *i or binary_­op(acc, *i) shall be implicitly convertible to InputIterator's value type. acc shall be writable to the result output iterator. In the ranges [first, last] and [result, result + (last - first)] binary_­op shall neither modify elements nor invalidate iterators or subranges.284

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Effects: For a non-empty range, the function creates an accumulator acc whose type is InputIterator's value type, initializes it with *first, and assigns the result to *result. For every iterator i in [first + 1, last) in order, acc is then modified by acc = acc + *i or acc = binary_­op(acc, *i) and the result is assigned to *(result + (i - first)).

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Returns: result + (last - first).

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Complexity: Exactly (last - first) - 1 applications of the binary operation.

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Remarks: result may be equal to first.

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The use of fully closed ranges is intentional.