Reduced row echelon form: Difference between revisions

=={{header|VBA}}==

{{trans|Phix}}<lang vb>Private Function ToReducedRowEchelonForm(M As Variant) As Variant

Dim lead As Integer: lead = 0

Dim rowCount As Integer: rowCount = UBound(M)

Dim columnCount As Integer: columnCount = UBound(M(0))

Dim i As Integer

For r = 0 To rowCount

If lead >= columnCount Then

Exit For

End If

i = r

Do While M(i)(lead) = 0

i = i + 1

If i = rowCount Then

i = r

lead = lead + 1

If lead = columnCount Then

Exit For

End If

End If

Loop

Dim tmp As Variant

tmp = M(r)

M(r) = M(i)

M(i) = tmp

If M(r)(lead) <> 0 Then

For t = LBound(M(r)) To UBound(M(r))

M(r)(t) = M(r)(t) / M(r)(lead)

Next t

End If

For j = 0 To rowCount

If j <> r Then

For t = LBound(M(j)) To UBound(M(j))

M(j)(t) = M(j)(t) - M(j)(lead) * M(r)(t)

Next t

End If

Next j

lead = lead + 1

Next r

ToReducedRowEchelonForm = M

End Function

Public Sub main()

r = ToReducedRowEchelonForm(Array( _

Array(1, 2, -1, -4), _

Array(2, 3, -1, -11), _

Array(-2, 0, -3, 22)))

For i = LBound(r) To UBound(r)

Debug.Print Join(r(i), vbTab)

Next i

End Sub</lang>{{out}}

<pre>1 0 0 -4

0 1 0 -11

0 0 1 22</pre>