From: ruby-core@...
Date: 2014-10-29T02:54:00+00:00
Subject: [ruby-dev:48719] [ruby-trunk - Feature #10056] [Closed] [PATCH 0/1]Add #adjugate method to matrix class

Issue #10056 has been updated by Marc-Andre Lafortune.

Category set to lib
Status changed from Assigned to Closed

Committed, thanks for this request!

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Feature #10056: [PATCH 0/1]Add #adjugate method to matrix class
https://bugs.ruby-lang.org/issues/10056#change-49706

* Author: gogo tanaka
* Status: Closed
* Priority: Normal
* Assignee: Marc-Andre Lafortune
* Category: lib
* Target version: 
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Add Matrix#adjugate to make a matrix adjugate.

Adjugate is really important operator to handle matrix (especially Exploring Data with ruby)

```ruby:
# Property

* Any n-th matrix  `m`(object of Matrix class) Satisfy the following conditions

Matrix.identity(n) == (m.adjugate * m) / m.det

# Differential vector or matrix
Let A = (a(i, j)) is n-th matrix, A(i, j) is adjugate matrix excluding the j and column i row A.

def. ∂det(A)/∂a(i,j) = (-1) ** (i + j) * det(A(i, j))
```

Some people regards adjugate matrix as Hermitian adjoint.

I regard adjuate matrix as transpose of the cofactor matrix by  referencing http://en.wikipedia.org/wiki/Adjugate_matrix.


---Files--------------------------------
add_matrix#adjugate_method.patch (2.22 KB)
update_news.patch (867 Bytes)
implement.patch (1.07 KB)
add_test.patch (1.84 KB)


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