# Multidimensional arrays

Multidimensional arrays can be defined as:

```ruby
var A = [
          [1, 2],
          [3, 4],
          [5, 6],
          [7, 8],
        ]

var B = [
          [1, 2, 3],
          [4, 5, 6],
        ]
```

In Sidef, we have the `Array.wise_op()` method, which takes two arbitrary nested arrays and an operator, folding each element (entrywise) with the provided operator, which is also available as `a ~Wop b`:

```ruby
say ([1,2,[3,[4]]] ~W+ [42,43,[44,[45]]])       #=> [43, 45, [47, [49]]]
```

Alternatively:

```ruby
say wise_op([1,2,[3,[4]]], '+', [42,43,[44,[45]]])   #=> [43, 45, [47, [49]]]
```

Scalar operations:

```ruby
A `scalar_add` 42   # scalar addition       (aliased as `sadd`)
A `scalar_sub` 42   # scalar subtraction    (aliased as `ssub`)
A `scalar_mul` 42   # scalar multiplication (aliased as `smul`)
A `scalar_div` 42   # scalar division       (aliased as `sdiv`)
```

This methods are provided by `Array.scalar_op()`, which, just like `Array.wise_op()`, also supports arbitrary nested arrays:

```ruby
say ([1,2,[3,[4]]] ~S+ 42)   #=> [43, 44, [45,  [46]]]
say ([1,2,[3,[4]]] ~S* 42)   #=> [42, 84, [126, [168]]]
```

...which is equivalent with:

```ruby
say scalar_op([1,2,[3,[4]]], '+', 42)  #=> [43, 44, [45,  [46]]]
say scalar_op([1,2,[3,[4]]], '*', 42)  #=> [42, 84, [126, [168]]]
```

## Iteration over 2D arrays

The extended `for-in` loop provides support for iterating over a 2D-array, which is useful in combination with the cross and zip metaoperators:

```ruby
for a,b in ([1,2] ~X [3,4]) {
    say "#{a} #{b}"
}
```

This is equivalent with:

```ruby
[[1,2], [3,4]].cartesian {|a,b|
    say "#{a} #{b}"
}
```

and outputs:

```
1 3
1 4
2 3
2 4
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://trizen.gitbook.io/sidef-lang/syntax_and_semantics/matrices.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.