simple-math-parser notes                               Revised: 120705
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1. Overview.

1.1. This  project provides a  CLI (i.e., non-GUI)  calculator program
written in pure Perl 5.

The  point  of  the project is to illustrate the structure of a simple
math parser. A recursive-descent approach is used.

1.2. Features:

* The program only needs Linux (or BSD UNIX)  and Perl 5.  No non-core
CPAN modules or external parser tools or libraries are required.

* PEMDAS compliant. For more information about this point, visit:

      http:https://en.wikipedia.org/wiki/PEMDAS

* Supports the four standard operators plus ** (exponentiation),  some
math functions  (sqrt, cbrt, log, sin, cos, and tan),  and a  few sym-
bolic constants (e, phi, and pi).

* Real numbers may optionally use scientific notation.

* The core consists of  a single  reasonably straightforward recursive
routine (ParseMath).

1.3. "simple-math-parser" was created by OldCoder:

      Site:    http:https://oldcoder.org/
      Mail:    [email protected]
      GitHub:  https://github.com/OldCoder/
      Repo:    https://github.com/OldCoder/simple-math-parser.git

The license used for the current version is  Creative Commons Attribu-
tion NonCommercial ShareAlike 3.0 Unported.

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2. Usage.

The program may be invoked as follows:

      simple-math-parser.pl EXPRESSION

Example:

      simple-math-parser.pl "1.5+(2/3)*pi-sqrt(2)"

Note that file permissions should be  set properly  before the program
is used. For example:

      chmod 755 simple-path-parser.pl

This is a CLI (i.e., non-GUI)  calculator program that takes a  single
arithmetic expression  as  an  argument, evaluates it,  and prints the
result to standard output.

If the expression is omitted,  the program will print usage documenta-
tion instead.

As a general rule, expressions should be quoted as shown here.  Other-
wise, "shell meta-character" problems may occur.

Numbers may  be  integers,  ordinary real numbers,  or real numbers in
scientific notation.  Examples of scientific notation: 1.3e+0 is equal
to 1.3, 12e-1 is equal to 1.2, and 5e+1 is equal to 50.  The + sign is
optional in this context.

Supported operators include:

+ (add), - (subtract or unary minus), * (multiply), / (divide), and **
(exponentiate).

Six functions are supported: sqrt (square root), cbrt (cube root), log
(natural logarithm),  sin, cos, and tan. The last three functions take
angles in radians.

Three standard constants may be used: e,  phi (the Golden Ratio),  and
pi.

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3. Development.

The source code consists of a single well-commented Perl 5 source file
named:

      simple-math-parser.pl

No  "build"  is required.  The source file is a script that's ready to
run.