calc
====
[GitHub](https://github.com/alfredxing/calc "A simple command-line calculator written in Go")
A simple, fast, and intuitive command-line calculator written in Go.
Install
-------
Install calc as you would any other Go program:
```bash
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`](https://godoc.org/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
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 n<sup>th</sup> 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.