Some other examples of nonlinear units are numerous different ring
sizes and wire gauges, the grit sizes used for abrasives, the decibel
scale, shoe size, scales for the density of sugar (e.g., baume).
The standard data file also supplies units for computing the area of a
circle and the volume of a sphere. See the standard units data file
for more details.
Wire gauges
with multiple zeroes are signified using negative numbers where two
zeroes is ‘`-1`’. Alternatively, you can use the synonyms ‘`g00`’,
‘`g000`’, and so on that are defined in the standard units data file.

You have: wiregauge(11) You want: inches * 0.090742002 / 11.020255 You have: brwiregauge(g00) You want: inches * 0.348 / 2.8735632 You have: 1 mm You want: wiregauge 18.201919 You have: grit_P(600) You want: grit_ansicoated 342.76923

The last example shows the conversion from P graded sand paper,
which is the European standard and may be marked “P600” on the back,
to the USA standard.
You can compute the area of a circle using the nonlinear unit,
‘`circlearea`’. You can also do this using the circularinch or
circleinch. The next example shows two ways to compute the area of a
circle with a five inch radius and one way to compute the volume of a
sphere with a radius of one meter.

You have: circlearea(5 in) You want: in2 * 78.539816 / 0.012732395 You have: 10^2 circleinch You want: in2 * 78.539816 / 0.012732395 You have: spherevol(meter) You want: ft3 * 147.92573 / 0.0067601492

The inverse of a nonlinear conversion is indicated by prefixing a tilde
(‘`~`’) to the nonlinear unit name:

You have: ~wiregauge(0.090742002 inches) You want: Definition: 11

You can give a nonlinear unit definition without an argument or
parentheses, and press <Enter> at the ‘`You want:`’ prompt to
get the definition of a nonlinear unit; if the definition is not valid
for all real numbers, the range of validity is also given. If the
definition requires specific units this information is also
displayed:

You have: tempC Definition: tempC(x) = x K + stdtemp defined for x >= -273.15 You have: ~tempC Definition: ~tempC(tempC) = (tempC +(-stdtemp))/K defined for tempC >= 0 K You have: circlearea Definition: circlearea(r) = pi r^2 r has units m

To see the definition of the inverse use the ‘`~`’ notation. In
this case the parameter in the functional definition will
usually be the name of the unit. Note that the inverse for
‘`tempC`’ shows that it requires units of ‘`K`’ in the
specification of the allowed range of values.
Nonlinear unit conversions are described in more detail in
Defining Nonlinear Units.