tweak the documentation

README.rst

@@ -44,9 +44,9 @@ science and engineering. SI scale factors make it possible to cleanly represent
 both very large and very small quantities in a form that is both easy to read 
 and write.  While generally better for humans, no general programming language 
 provides direct support for reading or writing quantities with SI scale factors, 
-making it difficult to write software that communicates effectively with humans.  
-*QuantiPhy* addresses this deficiency, making it natural and simple to both 
-input and output physical quantities.
+making it difficult to write numerical software that communicates effectively 
+with people.  *QuantiPhy* addresses this deficiency, making it natural and 
+simple to both input and output physical quantities.
 
 
 Features
@@ -72,13 +72,21 @@ quantities (`alternatives <https://kdavies4.github.io/natu/seealso.html>`_).
 However, as a rule, they focus on the units rather than the scale factors. In 
 particular, they build a system of units that you are expected to use throughout 
 your calculations.  These packages demand a high level of commitment from their 
-users and in turn provide unit consistency and built-in unit conversions.  In 
-contrast, *QuantiPhy* treats units basically as documentation.  They are simply 
-strings that are attached to quantities largely so they can be presented to the 
-user when the values are printed. As such, *QuantiPhy* is a light-weight package 
-that demands little from the user. It is used when inputting and outputting 
-values, and then only when it provides value. As a result, it provides 
-a simplicity in use that cannot be matched by the other packages.
+users and in turn provide unit consistency and built-in unit conversions.
+
+In contrast, *QuantiPhy* treats units basically as documentation.  They are 
+simply strings that are attached to quantities largely so they can be presented 
+to the user when the values are printed. As such, *QuantiPhy* is a light-weight 
+package that demands little from the user.  It is used when inputting and 
+outputting values, and then only when it provides value.  As a result, it 
+provides a simplicity in use that cannot be matched by the other packages.
+
+In addition, these alternative packages generally build their unit systems upon 
+the `SI base units <https://en.wikipedia.org/wiki/SI_base_unit>`_, which tends 
+to restrict usage to physical quantities with static conversion factors.  They 
+are less suited to non-physical quantities or conversion factors that change 
+dynamically, such as with currencies.  *QuantiPhy* gracefully handles all of 
+these cases.
 
 
 Quick Start

doc/index.rst

@@ -52,6 +52,8 @@ Features
 - Flexible unit conversion and scaling is supported to make it easy to convert 
   to or from any required form.
 - Provides a small but extensible collection of physical constants.
+- Supports the binary scale factors (*Ki*, *Mi*, etc.) along with the normal SI 
+  scale factors (*k*, *M*, etc.).
 
 
 Alternatives
@@ -86,8 +88,8 @@ Install with::
 
    pip3 install quantiphy
 
-Requires Python3.5 or newer.  If you using an earlier version of Python, install 
-version 2.10 of *QuantiPhy*.
+Requires Python 3.6 or newer.  If you using an earlier version of Python,
+install version 2.10 of *QuantiPhy*.
 
 You use *Quantity* to convert numbers and units in various forms to quantities:
 
@@ -135,7 +137,7 @@ the quantity:
    >>> str(Tboil)
    '100 °C'
 
-You can use the render method to flexibly convert the quantity to a string:
+You can use the *render* method to flexibly convert the quantity to a string:
 
 .. code-block:: python
 
@@ -154,6 +156,14 @@ You can use the render method to flexibly convert the quantity to a string:
    >>> Tboil.render(scale='°F')
    '212 °F'
 
+The *fixed* method is a variant that specializes in rendering numbers without 
+scale factors or exponents:
+
+.. code-block:: python
+
+   >>> cost.fixed(prec=2, show_commas=True, strip_zeros=False)
+   '$11,200,000.00'
+
 You can use the string format method or the new format strings to flexibly 
 incorporate quantity values into strings:
 
@@ -165,11 +175,14 @@ incorporate quantity values into strings:
    >>> f'{Fhy:.6}'
    '1.420406 GHz'
 
-   >>> f'«{Fhy:<15.6}»'
-   '«1.420406 GHz   »'
+   >>> f'❬{Fhy:<15.6}❭'
+   '❬1.420406 GHz   ❭'
+
+   >>> f'❬{Fhy:>15.6}❭'
+   '❬   1.420406 GHz❭'
 
-   >>> f'«{Fhy:>15.6}»'
-   '«   1.420406 GHz»'
+   >>> f'{cost:#,.2P}'
+   '$11,200,000.00'
 
    >>> f'Boiling point of water: {Tboil:s}'
    'Boiling point of water: 100 °C'