Reciprocal of a number (1/x)

Question

Challenge

Given a (floating-point/decimal) number, return its reciprocal, i.e. 1 divided by the number. The output must be a floating-point/decimal number, not just an integer.

Detailed specification

• You must receive input in the form of a floating-point/decimal number...
  • ...which has at least 4 significant digits of precision (if needed).
  • More is better, but does not count in the score.
• You must output, with any acceptable output method...
  • ...the reciprocal of the number.
  • This can be defined as 1/x, x⁻¹.
  • You must output with at least 4 significant digits of precision (if needed).

Input will be positive or negative, with absolute value in the range [0.0001, 9999] inclusive. You will never be given more than 4 digits past the decimal point, nor more than 4 starting from the first non-zero digit. Output needs to be accurate up to the 4th digit from the first non-zero one.

(Thanks @MartinEnder)

Here are some sample inputs:

0.5134
0.5
2
2.0
0.2
51.2
113.7
1.337
-2.533
-244.1
-0.1
-5

Note that you will never be given inputs which have above 4 digits of precision.

Here is a sample function in Ruby:

def reciprocal(i)
    return 1.0 / i
end

Rules

• All accepted forms of output are allowed
• Standard loopholes banned
• This is code-golf, shortest answer in bytes wins, but will not be selected.

Clarifications

• You will never receive the input 0.

Bounties

This challenge is obviously trivial in most languages, but it can offer a fun challenge in more esoteric and unusual languages, so some users are willing to award points for doing this in unusually difficult languages.

• @DJMcMayhem will award a +150 points bounty to the shortest brain-flak answer, since brain-flak is notoriously difficult for floating-point numbers

• @L3viathan will award a +150 points bounty to the shortest OIL answer. OIL has no native floating point type, nor does it have division.

• @Riley will award a +100 points bounty to the shortest sed answer.

• @EriktheOutgolfer will award a +100 points bounty to the shortest Sesos answer. Division in brainfuck derivatives such as Sesos is very difficult, let alone floating-point division.

• I (@Mendeleev) will award a bounty of +100 points to the shortest Retina answer.

If there's a language you think would be fun to see an answer in, and you're willing to pay the rep, feel free to add your name into this list (sorted by bounty amount)

Leaderboard

Here is a Stack Snippet to generate an overview of winners by language.

To make sure that your answer shows up, please start your answer with a headline, using the following Markdown template:

# Language Name, N bytes

where N is the size of your submission. If you improve your score, you can keep old scores in the headline, by striking them through. For instance:

# Ruby, <s>104</s> <s>101</s> 96 bytes

If there you want to include multiple numbers in your header (e.g. because your score is the sum of two files or you want to list interpreter flag penalties separately), make sure that the actual score is the last number in the header:

# Perl, 43 + 2 (-p flag) = 45 bytes

You can also make the language name a link which will then show up in the leaderboard snippet:

# [><>](http://esolangs.org/wiki/Fish), 121 bytes

var QUESTION_ID=114544,OVERRIDE_USER=62393;function answersUrl(e){return"https://api.stackexchange.com/2.2/questions/"+QUESTION_ID+"/answers?page="+e+"&pagesize=100&order=desc&sort=creation&site=codegolf&filter="+ANSWER_FILTER}function commentUrl(e,s){return"https://api.stackexchange.com/2.2/answers/"+s.join(";")+"/comments?page="+e+"&pagesize=100&order=desc&sort=creation&site=codegolf&filter="+COMMENT_FILTER}function getAnswers(){jQuery.ajax({url:answersUrl(answer_page++),method:"get",dataType:"jsonp",crossDomain:!0,success:function(e){answers.push.apply(answers,e.items),answers_hash=[],answer_ids=[],e.items.forEach(function(e){e.comments=[];var s=+e.share_link.match(/\d+/);answer_ids.push(s),answers_hash[s]=e}),e.has_more||(more_answers=!1),comment_page=1,getComments()}})}function getComments(){jQuery.ajax({url:commentUrl(comment_page++,answer_ids),method:"get",dataType:"jsonp",crossDomain:!0,success:function(e){e.items.forEach(function(e){e.owner.user_id===OVERRIDE_USER&&answers_hash[e.post_id].comments.push(e)}),e.has_more?getComments():more_answers?getAnswers():process()}})}function getAuthorName(e){return e.owner.display_name}function process(){var e=[];answers.forEach(function(s){var r=s.body;s.comments.forEach(function(e){OVERRIDE_REG.test(e.body)&&(r="<h1>"+e.body.replace(OVERRIDE_REG,"")+"</h1>")});var a=r.match(SCORE_REG);a&&e.push({user:getAuthorName(s),size:+a[2],language:a[1],link:s.share_link})}),e.sort(function(e,s){var r=e.size,a=s.size;return r-a});var s={};e.forEach(function(e){var o=e.language;/<a/.test(o)&&(o=jQuery(o).text().toLowerCase()),s[o]=s[o]||{lang:e.language,user:e.user,size:e.size,link:e.link,uniq:o}});var t=[];for(var o in s)s.hasOwnProperty(o)&&t.push(s[o]);t.sort(function(e,s){return e.uniq>s.uniq?1:e.uniq<s.uniq?-1:0});for(var c=0;c<t.length;++c){var i=jQuery("#language-template").html(),o=t[c];i=i.replace("{{LANGUAGE}}",o.lang).replace("{{NAME}}",o.user).replace("{{SIZE}}",o.size).replace("{{LINK}}",o.link),i=jQuery(i),jQuery("#languages").append(i)}}var ANSWER_FILTER="!t)IWYnsLAZle2tQ3KqrVveCRJfxcRLe",COMMENT_FILTER="!)Q2B_A2kjfAiU78X(md6BoYk",answers=[],answers_hash,answer_ids,answer_page=1,more_answers=!0,comment_page;getAnswers();var SCORE_REG=/<h\d>\s*([^\n,]*[^\s,]),.*?(\d+)(?=[^\n\d<>]*(?:<(?:s>[^\n<>]*<\/s>|[^\n<>]+>)[^\n\d<>]*)*<\/h\d>)/,OVERRIDE_REG=/^Override\s*header:\s*/i;

body{text-align:left!important}#language-list{padding:10px;width:290px;float:left}table thead{font-weight:700}table td{padding:5px}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <link rel="stylesheet" type="text/css" href="//cdn.sstatic.net/codegolf/all.css?v=617d0685f6f3"> <div id="language-list"> <h2>Winners by Language</h2> <table class="language-list"> <thead> <tr><td>Language</td><td>User</td><td>Score</td></tr></thead> <tbody id="languages"> </tbody> </table> </div><table style="display: none"> <tbody id="language-template"> <tr><td>{{LANGUAGE}}</td><td>{{NAME}}</td><td><a href="{{LINK}}">{{SIZE}}</a></td></tr></tbody> </table>

Answer 1

Perl 6, 3 bytes

1/*

Try it

This also works, but is 5 or 6 bytes
You can use ⁻ (superscript minus) at 3 bytes, or ¯ (macron) which is 2 bytes

*⁻¹

Try it

Answer 2

dc, 7 6 bytes

Edit: saved 1 byte thanks to Digital Trauma

7k1?/p

Try it online!

Because dc treats the input as commands, negative numbers are recognized using _ as the negative sign, instead of -, which is interpreted as the subtraction command. This is allowed by this meta consensus.

Explanation:

7k           # set precision to 7 digits. This is needed to output at least 4
             #significant figures when the input is '6431' for example)
1?           # push 1, then push input number
/p           # divide and print result

Answer 3

C++ lambda function, 24 bytes

[](float x){return 1/x;} 

Full program

#include <iostream>

void main()
{
    auto y = [](float x){return 1/x;} ;
    std::cout << y(5) << std::endl;
}

Answer 4

Rogex, 15 bytes

701300001600200

Try it online!

^{The actual language isn't on TIO yet, so a python 3.8 interpreter with the program in the code section and the python interpreter split in the header and footer is provided}

Rogex is a newly developed language that I've recently discovered, so I though I'd give it a crack and write an answer.

Explained

701 300 # Set the buffer to 1 and place it in cell 0
001     # Get numeric input and place it into the buffer
600 200 # Divide cell 0 (1) by the buffer (input) and print

(╭☞´• ᗜ •`)╭☞ 100 answers! Woot! (⌐■◡■)

Answer 5

Ruby, 10 bytes

->x{1.0/x}

Very simple

Answer 6

Quetzalcoatl, 3 bytes

cfI

c takes input, f converts to a float, and I takes the inverse.

Answer 7

Bean, 7 6 bytes

Equivalent JavaScript:

(1/A)

Bean xxd-style hexdump:

00000000: 4ca5 3a8e 2043                           L¥:. C

Explanation

A is auto-initialized with the 1st input line JSON-parsed. (e.g. 5 is interpreted as JSON and becomes a number), and the program implicitly outputs 1/A.

Edit The "hack" I just realized is that removing the first byte of the AST binary doesn't seem to affect the compilation of the program...

Try the demo here.

Answer 8

Forth, 3 bytes

1/f

Try it online

Takes a floating point literal, which in Forth must be in scientific notation, like 5e-4 for 0.0005 or 2e3 for 2000.0. The result will be left on the floating point stack.

Reference on number conversion in Forth.

Answer 9

Actually, 1 byte

ì

From the docs:

8D (ì): pop a: push 1/a

Try It Online

In Seriously, it would be two bytes:

,ì

Answer 10

Brachylog, 2 bytes

/₁

Try it online!

For the sake of completeness…

Explanation

/, by default, takes a list of 2 numbers [A, B] as input and unify its output with A divided by B.

When / has a subscript, it takes a single number as input unify its output with that number divided by the subscript. For example, /₄₂ will divide the input number by 42.

The only exception is if the subscript is 1 (because dividing by 1 is kind of useless). In that case, it unifies its output with the inverse of its input.

Answer 11

Java 7, 29 bytes

Golfed:

float i(float x){return 1/x;}

Ungolfed:

float i(float x)
{
    return 1 / x;
}

Pretty straight forward.

Answer 12

OCaml, 12

fun x->1./.x

The division of floats is done with the operator /..

Answer 13

bc + sh, 14 10 bytes

1/read()<NEWLINE>

Run bc with -l which sets the default scale to 20. That way both input and output have 20 digits after the decimal point.

Edit: Thanks DigitalTrauma for a tip on changing the answer from bc + sh to pure bc. Saved 4 bytes.

Answer 14

C#, 7 6 bytes

Saved a byte thanks to David Conrad.

x=>1/x;

Anonymous function which returns the inverse of a number.

Full program with test cases:

using System;

public class Program
{
    public static void Main()
    {
        Func<double, double> f =
        x=>1/x;
        
        // test cases:
        Console.WriteLine(f(0.5134));
        Console.WriteLine(f(0.5));
        Console.WriteLine(f(2));
        Console.WriteLine(f(2.0));
        Console.WriteLine(f(0.2));
        Console.WriteLine(f(51.2));
        Console.WriteLine(f(113.7));
        Console.WriteLine(f(1.337));
        Console.WriteLine(f(-2.533));
        Console.WriteLine(f(-244.1));
        Console.WriteLine(f(-0.1));
        Console.WriteLine(f(-5));
    }
}

Answer 15

PHP, 24 bytes

echo(1/(float)$argv[1]);

This is my first answer, tell me if I can somehow shorten it! Try it online!

When trying it online, just change the argument to the desired number n of which you want to get 1/n

Very straightforward approach.

Answer 16

Common Lisp, 1 byte

/

Try it online!

Answer 17

Julia, 3 bytes

3 bytes saved thanks to @gggg

inv

Try it online!

Returns the matrix inverse.

Answer 18

Vyxal, 1 byte

Ė

Try it Online!

Answer 19

Kotlin, 6 bytes

{1/it}

Attempt This Online!

Simple anonymous function.

Answer 20

CJam, 4 bytes

1rd/

Try it online!

1     e# Push 1
 rd   e# Push input as a double
   /  e# Divide

Alternate solution:

rdW#

rd    e# Push input as a double
  W   e# Push -1
   #  e# Exponentiation

Answer 21

Fortran 95, 23 bytes

function f(x)
f=1/x
end

Answer 22

Mathics, 4 bytes

1/#&

Try it online!

Answer 23

QBIC, 5 bytes

:?1/a

Explanation:

:    get input from the cmd line, named 'a'
?    PRINT
1/a  1/a

Answer 24

Scala, 3 bytes

1/_

This defines a lambda equivalent to x => 1/x (_ is a placeholder for the argument). Use by assigning it to a variable, then calling it, like this:

val f: Double => Double = 1/_
f(5) // 0.2

Answer 25

Racket, 11 bytes

(/ 1(read))

Try it online!

Answer 26

PHP, 11

<?=1/$argn;

Run with echo <n> | php -nR '<code

Answer 27

Excel VBA, 7 Bytes

Anonymous VBE immediates window function that takes input from cell [A1] of type variantand expecting a (floating-point) number and outputs its inverse to the VBE immediates window. Does not handle improperly formatted input.

?1/[A1]

Answer 28

TI-Basic, 2 bytes

Ansֿֿ ¹

You could also do 1/Ans (3) or Ans^~1 (4).

Answer 29

Noodel, 1 byte

ẹ

A command that takes the first character of a string and places at the end, for numbers takes the reciprocal of the number. The interpreter for Noodel is written in JavaScript which has double precision floating point numbers.

Try it:)

---

How it works

  # Implicitly pushes the number onto the stack.
ẹ # Takes the reciprocal of the input.
  # Implicitly prints the top of the stack to the screen.

Answer 30

Scala, 15 Bytes

(x:Double)=>1/x

Don't think there's a shorter way to do this in Scala.