Command Line Interface (CLI) #

When math.js is installed globally using npm, its expression parser can be used from the command line. To install math.js globally:

$ npm install -g mathjs

Normally, a global installation must be run with admin rights (precede the command with sudo). After installation, the application mathjs is available via the command line:

$ mathjs
> 12 / (2.3 + 0.7)
4
> 12.7 cm to inch
5 inch
> sin(45 deg) ^ 2
0.5
> 9 / 3 + 2i
3 + 2i
> det([-1, 2; 3, 1])
-7

The command line interface can be used to open a prompt, to execute a script, or to pipe input and output streams:

$ mathjs                                 # Open a command prompt
$ mathjs script.txt                      # Run a script file, output to console
$ mathjs script1.txt script2.txt         # Run two script files
$ mathjs script.txt > results.txt        # Run a script file, output to file
$ cat script.txt | mathjs                # Run input stream, output to console
$ cat script.txt | mathjs > results.txt  # Run input stream, output to file

You can also use it to create LaTeX from or sanitize your expressions using the --tex and --string options:

$ mathjs --tex
> 1/2
\frac{1}{2}

$ mathjs --string
> (1+1+1)
(1 + 1 + 1)

To change the parenthesis option use the --parenthesis= flag:

$ mathjs --string --parenthesis=auto
> (1+1+1)
1 + 1 + 1

$ mathjs --string --parenthesis=all
> (1+1+1)
(1 + 1) + 1

Command line debugging (REPL) #

The library also provides a REPL (Read Evaluate Print Loop) via bin/repl.js which loads mathjs in a Node.js command line environment. You can either start it directly (./bin/repl.js) or via node (node bin/repl.js).

You can exit using either [ctrl]-[C] or [ctrl]-[D].

$ ./bin/repl.js 
> math.parse('1+1')
{ op: '+',
  fn: 'add',
  args: 
   [ { value: '1', valueType: 'number' },
     { value: '1', valueType: 'number' } ] }
> 