The objects in a set are also called the elements, or members, of the set. A set is said to contain its elements. Null Set: There are no anything in the set
复旦大学：《数学物理方法 Methods of Mathematical Physics》课程教学资源（教学研究）Understanding the power reflection and transmission coefficients of a plane wave at a planar interface
Introduction Definition Induced Norm–Matrix p-Norms One Norm Infinity Norm Norm of a Product Two Norm Frobenius Norm Norm of a Submatrix Exercises Comprehensive Problems
