c# - System.Numerics.Vector.ConditionalSelect 的用途是什么？

Question

谁能更好地举例说明 System.Numerics.Vector.ConditionalSelect 可以使用什么/何时/如何使用？

我对 docs 的了解不多.

Answer 1

condition参数实际上是Vector<int>当使用 ConditionalSelect 的 4 字节重载时例如带有 Vector<int> 的那些或 Vector<float>争论。 condition是Vector<long>当使用 8 字节版本等时

要扩展@Hans 在您的问题中的评论，condition意思是这样的:double c = cond == -1 ? a : b; .也就是说，当cond == -1 , 它选择左边的值。当cond == 0 ，它会选择正确的值。

当 cond是另外一回事，我看到了一些我还不是特别了解的结果，并没有真正研究。

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>}
    }
}