由 C++ STL 卷积

Question

是否有一个很好的算法实现来计算 C++ STL(或什至提升)中两个范围的卷积？即带有原型(prototype)的东西(两个范围 a..b 和 c..d 的卷积):

template< class Iterator >
void convolution(Iterator a, Iterator b, Iterator c, Iterator d);

修改 a..b 范围

Answer 1

是 std::transform

std::transform(a, b, c, a, Op);

// a b is the the first input range
// c   is the start of the second range (which must be at least as large as (b-a)
// 
// We then use a as the output iterator as well.

// Op is a BinaryFunction

回复评论中关于如何进行状态累加的评论:

struct Operator
{
    State& state;
    Operator(Sate& state) : state(state) {}
    Type operator()(TypeR1 const& r1Value, TypeR2 const& r2Value) const
    {
        Plop(state, r1Value, r2Value);
        return Convolute(state, r2Value, r2Value);
    }
};
State  theState  = 0;
Operator Op(theState);