Qalculate! library and CLI

Qalculate! is a multi-purpose cross-platform desktop calculator. It is simple
to use but provides power and versatility normally reserved for complicated
math packages, as well as useful tools for everyday needs (such as currency
conversion and percent calculation). Features include a large library of
customizable functions, unit calculations and conversion, symbolic calculations
(including integrals and equations), arbitrary precision, uncertainty
propagation, interval arithmetic, plotting, and a user-friendly interface (GTK+,
Qt, and CLI).

1. Requirements

* GMP and MPFR
* libxml2
* libcurl, icu, gettext (recommended)
* iconv, readline (recommended for CLI)
* Gnuplot 1.7 (optional)
* doxygen (optional)

For Linux distributions which provide separate development packages, these must
be installed for all the required libraries (e.g. libmpfr-dev) before
compilation.

2. Installation

In a terminal window in the top source code directory run

* ./autogen.sh (not required if using a release source tarball, only if using
  the git version)
* ./configure
* make
* make install (as root)
* ldconfig (if necessary, as root)

If libqalculate is installed in /usr/local (default) you may need to add
/usr/local/lib to the library path of the system (add /usr/local/lib to a file
under /etc/ld.so.conf.d/ and run ldconfig).

3. API Documentation

The API documentation is included in the package and is installed in
$docdir/libqalculate/html (usually /usr/share/doc/libqalculate/html).
It is generated when running autogen.sh.

It is also available online at reference/index.html.

4. Using the CLI program "qalc"

To calculate a single expression from the command line (non-interactive mode)
enter "qalc EXPRESSION" (e.g. qalc 5+2)

"qalc --help" shows information about command line options in non-interactive
mode.

If you run "qalc" without any mathematical expression the program will start in
interactive mode, where you can enter multiple expressions with history and
completion, manipulate the result and change settings.

Type "help" in interactive mode for more information.

A man page is also available (shown using the command "man qalc", or online at
https://qalculate.github.io/manual/qalc.html).

5. Other Applications

The main user interfaces for libqalculate are
qalculate-gtk (https://github.com/Qalculate/qalculate-gtk) and
qalculate-qt (https://github.com/Qalculate/qalculate-qt).

Other software using libqalculate include
* Qalculator web app (https://qalculator.xyz/) (also available as apps for Android, iOS, and Windows)
* Qalculate for Android (https://github.com/jherkenhoff/qalculate-android)
* KDE Plasma Workspace (https://www.kde.org/workspaces/plasmadesktop/)
* Cantor (http://kde.org/applications/education/cantor/)
* Step (http://kde.org/applications/education/step/)
* Qalculate widget for KDE Plasma (https://store.kde.org/p/1155946/)


6. Features

General
   * All common operators — arithmetic, logical, bitwise, element-wise, (in)equalities
   * Expressions may contain any combination of numbers, constants, functions, units, variables, matrices, vectors, and time/dates
   * Fault-tolerant and flexible input parsing with verbose error/warning messages
   * Calculate as you type
   * Arbitrary precision with both rational and floating point numbers
   * Complex and infinite numbers
   * Propagation of uncertainty and interval arithmetic
   * Both exact and approximate output (sqrt(32) = 4 * sqrt(2) ≈ 5.657)
   * Simple and mixed fractions (4 / 6 * 2 = 1.333... = 4/3 = 1 + 1/3)
   * All common number bases, as well as negative and non-integer radices, roman numerals, etc.
   * RPN mode
   * Highly customizable with a myriad of options for every aspect of the calculator

Symbolic calculations
   * Factorization and simplification
   * Differentiation and integration
   * Can solve most equations and inequalities
   * Customizable assumptions (e.g. ln(2x) where x > 0 = ln(2) + ln(x))

Functions
   * Over 400 flexible and diverse functions (trigonometry, exponents and logarithms, combinatorics, geometry, calculus, statistics, finance, time and date, etc.)
   * Easily created and edited from the user interfaces, with support for different argument types, subfunctions, and custom conditions

Units
   * Over 400 diverse units and all standard decimal and binary prefixes
   * Includes all SI units, as well as imperial, CGS, atomic, and natural units, and more...
   * Automatic and explicit conversion (e.g. ft + yd + m = 2.2192 m, 5 kg * m/s^2 = 5 N, 5 m/s to mph = 11.18 mph)
   * Currency conversion with daily updated exchange rates
   * Easily created and edited from the user interfaces

Variables and constants
   * All common basic constants (pi, e, etc.)
   * Fundamental physical constants with 2022 CODATA values (including standard uncertainy and optional units)
   * CSV file import and export
   * Easily created and edited from the user interfaces (including by direct assignment, e.g. x = 2 s)
   * Data sets with objects and associated properties in database-like structure (data set with chemical elements is included)

Plots and graphs
   * Uses Gnuplot
   * Can plot functions or data (matrices and vectors)
   * Can be customized using several options, and saved as image files

...and more...

