In physics, particularly in quantum field theory, configurations of a physical system that satisfy classical equations of motion are called "on the mass shell" or simply more often on shell; while those that do not are called "off the mass shell", or off shell. In quantum field theory, virtual particles are termed off shell … Ver mais Mass shell is a synonym for mass hyperboloid, meaning the hyperboloid in energy–momentum space describing the solutions to the equation: $${\displaystyle E^{2}- {\vec {p}}\, ^{2}c^{2}=m_{0}^{2}c^{4}}$$ the Ver mais An example comes from considering a scalar field in D-dimensional Minkowski space. Consider a Lagrangian density given by $${\displaystyle {\mathcal {L}}(\phi ,\partial _{\mu }\phi )}$$. … Ver mais 物理学、主に場の量子論において、古典力学的運動方程式を満たす物理系の構成を、オンシェル(on shell)と呼び、そうでないものをオフシェル(off shell)と呼ぶ。 例えば作用の定式化の中での古典力学では、変分原理の極値解はオンシェル（質量殻） であり、オイラー＝ラグランジュ方程式はオンシェルの方程式である（すなわち、それらはオフシェルでは成り立たない）。ネーターの定理もまた、オンシェルの定理である。
scripting - How to use and/or conditional in shell script
Web30 de set. de 2010 · I want to represent multiple conditions like this: if [ ( $g -eq 1 -a "$c" = "123" ) -o ( $g -eq 2 -a "$c" = "456" ) ] then echo abc; else e... WebHá 6 horas · BYD Europe and Shell EV Charging Solutions have entered into a cooperation to offer at least 100,000 BYD customers in Europe access to DC and HPC charging on the Shell Recharge network with special conditions. Those who purchase a BYD all-electric car or plug-in hybrid will receive a so-called Platinum… danish kids furniture
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Web14 de mar. de 2010 · setting the variable to either 0 or 1 based on the condition: (as the question's example suggests.) The general form would read (condition); variable=$?; … Web16 de out. de 2011 · As noted elsewhere in this thread, the original question basically answers itself. Here is an illustration showing that if conditions may also be nested. This example uses if to check if a file exists and if it is a regular file. If those conditions are true, then check whether or not it has a size greater than 0. birthday calculator math cats