c# - System.Numerics.Vector.ConditionalSelect 用于什么？

Question

谁能用一个例子最好地解释一下什么/何时/如何System.Numerics.Vector.ConditionalSelect使用？

我无法从文档中了解很多。

Answer 1

该condition参数实际上是Vector<int>在使用 4 字节重载时使用的，ConditionalSelect例如带有Vector<int>或Vector<float>参数的那些。condition是Vector<long>在使用 8 字节版本等时。

要在您的问题中扩展@Hans 的评论，condition意思是：double c = cond == -1 ? a : b;。也就是说，当 时cond == -1，它选择左边的值。当 时cond == 0，它选择正确的值。

什么时候cond是别的，我看到了一些我还不是特别了解并且没有真正研究过的结果。

class Program
{
    static void Main(string[] args)
    {
        //Length depends on your Vector<int>.Count. In my computer it is 4
        Vector<int> vector1 = new Vector<int>(4); //vector1 == {<4, 4, 4, 4>}
        Vector<int> vector2 = new Vector<int>(5); //vector2 == {<5, 5, 5, 5>}
        Vector<int> mask = Vector.GreaterThan(vector1, vector2); //mask == {<0, 0, 0, 0>}
        Vector<int> selected = Vector.ConditionalSelect(mask, vector1, vector2); //selected == {<5, 5, 5, 5>}

        vector1 = new Vector<int>(4); //vector1 == {<4, 4, 4, 4>}
        vector2 = new Vector<int>(3); //vector2 == {<3, 3, 3, 3>}
        mask = Vector.GreaterThan(vector1, vector2); //mask == {<-1, -1, -1, -1>}
        selected = Vector.ConditionalSelect(mask, vector1, vector2); //selected == {<4, 4, 4, 4>}

        mask = new Vector<int>(123); //mask == {<123, 123, 123, 123>}
        selected = Vector.ConditionalSelect(mask, vector1, vector2); //selected == {<0, 0, 0, 0>}

        mask = new Vector<int>(4);
        selected = Vector.ConditionalSelect(mask, vector1, vector2); //selected == {<7, 7, 7, 7>}
    }
}