> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/p/polynomial_regression.md).

# Polynomial regression

```ruby
func regress(x, y, degree) {
    var A = Matrix.build(x.len, degree+1, {|i,j|
        x[i]**j
    })

    var B = Matrix.column_vector(y...)
    ((A.transpose * A)**(-1) * A.transpose * B).transpose[0]
}

func poly(x) {
    3*x**2 + 2*x + 1
}

var coeff = regress(
    10.of { _ },
    10.of { poly(_) },
    2
)

say coeff
```

## Output:

```
[1, 2, 3]
```