Module physical_quantity::predefined::unit

source · [−]
Expand description

Default unit definition.

Base Unit

This definition uses the following units as base units.

  • Length Metre (m)
  • Mass Gram (g)
  • Time Second (s)
  • Temperature Kelvin (K)
  • Amount Mole (mol)
  • Current Ampere (A)
  • Luminous Candela (cd)

Only mass base unit is different from the SI standards for ease of parse.

Dimensionless

This definition defines some hyphen-like letters to represent the dimensionless dimension because the minus sign (-\u{002D}) cannot compose the Name.

Angle

This definition defines one rotation as one (1).

Some units represent pressure as the hight of liquid column. This definition defines Hg(mercury) and Aq(water). These units are given Pressure / Length dimension. To use these units for pressure unit, multiply length unit. (e.g. “mm Hg”, “in. Aq”) These units are written with no spaces as “mmHg”, “inHg” ordinary. If these spaces are bothering you, zero width space can help. (e.g. “mm​Hg”, “in.​Aq”)

Deprecated But Acceptable

Unicode has many curious characters which represent units. These characters are deprecated because existing only for compatibility. However, this definition adopts these characters positively. Why? Just fun, that’s all.

Illegal But Acceptable

The SI Standards does not allow a orphan Prefix. This definition also. But having said that, any Name can promote with Prefix. Yes, we can put the Prefix to the dimensionless dimension! (e.g. “M—” (Mega dimensionless??)) This is useful for expressing notations such as “x106”.

A similar case is a double Prefix , which is not allowed in the [SI Standard]. Of course, the syntax of this package implements disallows it also, but some CJK compatible characters which represent the unit include a Prefix already. As a result of this, this definition allows some double prefix. (e.g. “c㎎” (centi milli gram?? (= 10-5g))) I can’t think of a use for it, though.

Constants

DEFAULT_UNIT_DEF

Default unit definition table.