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## Feature #17769

closed

### Proposal: numeric coefficient syntax

Status:
Rejected
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:103140]
Tags:

Description

When we write a mathematical equation, we often omit a multiplication operator between a coefficient and a variable like `2x`.
I guess this convention can be useful in computer programming. Practically, Julia employs this notation:

```julia> 2pi
6.283185307179586

julia> x = 3
3

julia> 2x
6

julia> pi
π = 3.1415926535897...

julia> 2pi
6.283185307179586
```

I wrote a proof-of-concept patch to introduce this notation in Ruby.
We can write the following with this patch:

```irb(main):001:0> x = 3
=> 3
irb(main):002:0> 2x
=> 6
irb(main):003:0> def pi = Math::PI
=> :pi
irb(main):004:0> 2pi
=> 6.283185307179586
```

Files

Actions #1

#### Updated by mame (Yusuke Endoh)about 2 months ago

• Tags set to joke

#### Updated by matz (Yukihiro Matsumoto)about 2 months ago

```i = 10
p 2i # => 20 or Complex(0,2)?
```

Matz.

#### Updated by mrkn (Kenta Murata)about 2 months ago

`2i` is an imaginary number literal so it is `Complex(0, 2)`.

Actions #4

#### Updated by mrkn (Kenta Murata)about 2 months ago

• File deleted (num_coeff.patch)

#### Updated by mrkn (Kenta Murata)about 2 months ago

I replaced the attached patch with changes to accept not only `2x` but also `2(x + 1)`.

#### Updated by mrkn (Kenta Murata)about 2 months ago

Replace the patch with refactoring.

Actions #7

#### Updated by mrkn (Kenta Murata)about 2 months ago

• File deleted (num_coeff.patch)
Actions #8

#### Updated by mrkn (Kenta Murata)about 1 month ago

• Status changed from Open to Rejected
Actions

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