来源于真实人名的英语词汇

英语中不少的词起源于人名,有的来自小说中人物的名字.有的则由真实人物的名字演变成普通名词,如:sandwich(三明冶)原是181世纪60年代用来给赌桌上的桑德威奇四世(the fourth Earl ofSandwich)充饥的夹肉面包;wellington(一种长至膝盖的靴子)是由英国著名的惠灵顿公爵(the Duke ofWellington)的名字命名的.现在一般称为 wellies(惠灵顿长靴)。

Difference Discrete Variational Principles, Euler?Lagrange Cohomology and Symplectic, Multisymplectic Structures III: Application to Symplectic and Multisymplectic Algorithms

In the previous papers I and II, we have studied the difference discrete variational principle and the Euler?Lagrange cohomology in the framework of multi-parameter differential approach. We have gotten the difference discrete Euler?Lagrange equations and canonical ones for the difference discrete versions of classical mechanics and field theory as well as the difference discrete versions for the Euler?Lagrange cohomology and applied them to get the necessary and sufficient condition for the symplectic or multisymplectic geometry preserving properties in both the Lagrangian and Hamiltonian formalisms. In this paper, we apply the difference discrete variational principle and Euler?Lagrange cohomological approach directly to the symplectic and multisymplectic algorithms. We will show that either Hamiltonian schemes or Lagrangian ones in both the symplectic and multisymplectic algorithms are variational integrators and their difference discrete symplectic structure-preserving properties can always be established not only in the solution space but also in the function space if and only if the related closed Euler?Lagrange cohomological conditions are satisfied.

解构简约

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