The distinction between covariance and contravariance is important for computations with tensors, which often have mixed variance.
协变和逆变的区别对于张量的计算尤为重要，这往往会出现混合方差。
2
In the meantime, I further elucidated the compatibility, incompatibility and contravariance of the mathematical concept.
同时，还进一步阐明了数学概念的兼容性、非兼容性和反变性。
3
Note that although the above examples show how to declare covariance and contravariance for delegate types, it's not different to do so with interfaces.