World-views in the SIunits package

Abstract

The SIunits package allows for the use of world views other than the standard (std) view of dimensional quantities length, time, mass, current, temperature, and so forth. A commonly used world view says ``work in units where c = 1,'' for example. The package must do the work to support that new relativistic world view. In this note, the author provides concrete answers to several questions: What set of statements defines a world view? What does the SIunits Package need to know to be able to support each world view? How can this information be derived from the defining statements, in the general case? and Where are these computations and derivations done in the SIunits package? As a starting point, the author describes the std world view as having N{sub d} dimensioned units labeled f{sub a}. Thus f{sub 1} is a meter, f{sub 2} a kilogram, f{sub 3} a second, and so forth. N{sub d} is seven but that is moot; were they to eliminate Luminosity and/or Amount of Substance, for instance, the arguments in this note would remain unchanged.