Issue #10056 has been updated by gogo tanaka.
File update_news.patch added
File implement.patch added
File add_test.patch added
@Tomoyuki C. san
Sorry for my delay. I was little bit puzzled about how to test well.
I suppose it’s better to add not only #adjugatebut all of such a
testcase about properties by instance variable.
I’m gonna make another ticket 
Right now, I added testcase for Matrix#adjugate and separated patches.
It ready for merging.
Take your time.
Feature #10056: [PATCH 0/1]Add #adjugate method to matrix class
- Author: gogo tanaka
- Status: Assigned
- Priority: Normal
- Assignee: Marc-Andre L.
- Category:
- Target version:
Add Matrix#adjugate to make a matrix adjugate.
Adjugate is really important operator to handle matrix (especially
Exploring Data with 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 Adjugate matrix - Wikipedia.
—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)