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§7.3 · zh-CN · translation · unreviewed
在给出一般张量分量的变换律之前,先建立一种称为 核心指标记法(kernel index notation) 的约定是有益的。在这种记法中,我们用带撇的指标表示变换后的基和对偶基上的指标,即 和 。在“核”字母 和 上加撇本质上是多余的,去掉它们几乎不会损失什么含义,只需将变换后的基写作 和 。该约定甚至可以更进一步,要求带撇的指标在一个自然数的指标集 上取值。这些做法可能显得有些古怪,也可能造成混淆。因此,我们只采用一种“半成熟”的核心指标记法,其关键要求是对变换后的量使用带撇的指标。核心指标记法的主要优点是使张量的变换律更容易记忆。
§7.3 · en · original_transcription · unreviewed
Before giving the transformation law of components of a general tensor it is useful to establish a convention known as the kernel index notation. In this notation we denote the indices on the transformed bases and dual bases by a primed index, and . The primes on the ‘kernel’ letters and are essentially superfluous and little meaning is lost in dropping them, simply writing and for the transformed bases. The convention may go even further and require that the primed indices range over an indexed set of natural numbers . These practices may seem a little bizarre and possibly confusing. Accordingly, we will only follow a ‘half-blown’ kernel index notation, with the key requirement that primed indices be used on transformed quantities. The main advantage of the kernel index notation is that it makes the transformation laws of tensors easier to commit to memory.