Skip to content

Latest commit

 

History

History
77 lines (54 loc) · 3 KB

README.md

File metadata and controls

77 lines (54 loc) · 3 KB
Raw

calc

A very minimalistic Python calculator. Actually, it's only the standard Python interpreter with import * from math and some physical constants defined. In practice, I feel that more than that (GUIs, special syntax, …) is just unnecessary for a quick and simple calculator.

Not especially groundbreaking stuff, but I've been using it for years, so maybe someone will find its simplicity useful.

Requirements

  • A shell
  • Python

Usage

  • calc by itself goes to interactive mode by starting the interpreter.

  • Expressions can be given as an argument:

     $ calc e**pi-pi
 19.9990999792
 $

  • …or as STDIN:

      $ echo 'ln(-e*cos(pi))*sqrt(256)' | calc
  >>> -16.0
  >>> 
  $

Notes

  • Tab completion is enabled:

      >>> def extension(L, E, h, A, q):
  ...     return q*L**3/(8*h*E*A)*(1+16*h**2/(3*L))
  ... 
  >>> alvsborgsbron=(417.6, 190e9, 52.6, .22, 210e3)
  >>> golden_gate=(1280, 198e9, 143, .54, 185e3)

    Now, ext <Tab> (*alv <Tab> ) <Enter> gives:

      >>> extension(*alvsborgsbron)
  31.5920944757691

    and so on. If one is used to the shell, this is as intuitive as can be.

  • ↑/↓ walks through command history, and other standard text navigation idioms are followed (Ctrl+W, Ctrl+U, Home, End, Ctrl+←/→, etc.).

  • _ holds the previously returned result in the interpreter. Useful in many respects, e.g.:

      >>> m = 80
  >>> v = 20
  >>> m*v**2
  32000
  >>> E_k = _
  >>> E_k
  32000

  • x^y is not "x to the power of y" in Python, but the binary XOR operator. x**y, however, is exactly "x to the power of y". This can be overridden, but I'd rather stay close to the Python syntax.

  • Make use of Python's standard language features where it fits. Variable declaration, lists, built-in functions (sum(), divmod(), range(), …), defining quick functions, etc. Also check what the math module provides by e.g. running import math; help(math) in a Python interpreter.

  • Using Fluxbox, I have defined

      Mod4 c    :ExecCommand urxvtc -e calc

    in my ~/.fluxbox/keys to start a terminal with calc via a simple keyboard shortcut. Useful enough that it should be a standard feature in most window managers, I believe :-) .

  • Extra modules can easily be imported when needed, e.g. itertools, random, NumPy or matplotlib.

And remember that everything is just Python, so after noting how powerful and easy to use the Python interpreter is in this respect, just write script files for more complicated calculations. One can come a long way without Matlab.

Upstream

https://github.com/dandersson/calc

License

GPL version 2 or later.