dotnet-core/release-notes/2.1/Preview/api-diff/preview2/2.1-preview2_System.Numerics.md

System.Numerics

 namespace System.Numerics {
     [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
     public struct Vector<T> : IEquatable<Vector<T>>, IFormattable where T : struct {
+        public Vector(Span<T> values);
     }
 }