A simple, fast command-line calculator written in Go
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Latest commit 0b39213 Jan 13, 2017 @alfredxing committed on GitHub Merge pull request #17 from LukasMa/master
Wired linebreaks when using fmt.Print() functions in custom terminal

README.md

calc

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A simple, fast, and intuitive command-line calculator written in Go.

Install

Install calc as you would any other Go program:

go get github.com/alfredxing/calc

Usage

You can use calc in two ways: shell mode and command.

Shell mode

This is probably the mode you'll want to use. It's like the python shell or irb. The shell mode uses the terminal package provided by golang.org/x/crypto/ssh/terminal, which means it supports many of the shell features you know and love (like history, pasting, and the exit command).

> 1+1
2
> 3(5/(3-4))
-15
> 3pi^2
29.608813203268074
> @+1
30.608813203268074
> @@@*2
-30
> ln(-1)
NaN

Command

You can also use calc to evaluate an expression with just a single command (i.e. without opening the shell). To do this, just use calc [expression]:

bash$ calc 1+1
2
bash$

Supported functions, operators, and constants

calc supports all the standard stuff, and I'm definitely adding more later (also feel free to fork and add your own!)

Operators

+, -, *, /, ^, %

Functions

sin, cos, tan, cot, sec, csc, asin, acos, atan, acot, asec, acsc, sqrt, log, lg, ln, abs

Constants

e, pi, π

History

Previous results can be accessed with the @ symbol. A single @ returns the result of the last computation, while multiple @ gets the nth last result, where n is the number of @s used (for example, @@ returns the second-last result, @@@@@ returns the fifth-last result).

Why not use ...?

  • Google
    • Doesn't work without an internet connection
    • Slower
    • Doesn't show previous computations, so you end up with multiple tabs open at once.
  • Spotlight (on OS X)
    • No history
    • Switching between Spotlight and other windows isn't too fun
  • Python/IRB
    • Requires use of a separate math module for most functions and constants
    • A little bit slower to start up
  • bc
    • Limited number of built-in functions; these have shortened (not too intuitive) names as well.

The alternatives above are all great, and have their own advantages over calc. I highly recommend looking into these if you don't like how calc works.