Subscripts and indices




Subscripts are used for two reasons, to simply attach a name to the quantity or associate it with another quantity, or represent a specific vector, matrix, or tensor component.clarification needed

  • Name reference: The quantity has a subscripted or superscripted single letter, group of letters, or complete word, to label what concept or entity they refer to, often to distinguish it from other quantities with the same main symbol. These subscripts or superscripts tend to be written in upright roman typeface rather than italic while the main symbol representing the quantity is in italic. For instance Ek or Ekinetic is usually used to denote kinetic energy and Ep or Epotential is usually used to denote potential energy.
  • Quantity reference: The quantity has a subscripted or superscripted single letter, group of letters, or complete word, to parameterize what measurement/s they refer to. These subscripts or superscripts tend to be written in italic rather than upright roman typeface; the main symbol representing the quantity is in italic. For example cp or cpressure is heat capacity at the pressure given by the quantity in the subscript.

The type of subscript is expressed by its typeface: 'k' and 'p' are abbreviations of the words kinetic and potential, whereas p (italic) is the symbol for the physical quantity pressure rather than an abbreviation of the word.

  • Indices: The use of indices is for mathematical formalism using index notation.

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