[2005] help understanding how to use this module plz

[lplover2k]

i want to find the eigenvectors and eigenvalues for a matrix... can someone help me use this module from

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'This code is generated by the AlgoPascal translator
'
'This code is distributed under the ALGLIB license
'    (see [url]http://www.alglib.net/copyrules.php[/url] for details)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'This routines must be defined by the programmer
' Function TridiagonalEVD(ByRef D() As Double, _
'         ByRef E_() As Double, _
'         ByVal N As Long, _
'         ByVal ZNeeded As Long, _
'         ByRef Z() As Double) As Boolean
' Sub ToTridiagonal(ByRef A() As Double, _
'         ByVal N As Long, _
'         ByVal IsUpper As Boolean, _
'         ByRef Tau() As Double, _
'         ByRef D() As Double, _
'         ByRef E() As Double)
' Sub UnpackQFromTridiagonal(ByRef A() As Double, _
'         ByRef N As Long, _
'         ByRef IsUpper As Boolean, _
'         ByRef Tau() As Double, _
'         ByRef Q() As Double)
 
 
'Routines
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'Finding the eigenvalues and eigenvectors of a symmetric matrix
'
'The algorithm finds eigen pairs of a symmetric matrix by reducing it to
'tridiagonal form and using the QL/QR algorithm.
'
'Input parameters:
'    A       -   symmetric matrix which is given by its upper or lower
'                triangular part.
'                Array whose indexes range within [1..N, 1..N].
'    N       -   size of matrix A.
'    IsUpper -   storage format.
'    ZNeeded -   flag controlling whether the eigenvectors are needed or not.
'                If ZNeeded is equal to:
'                 * 0, the eigenvectors are not returned;
'                 * 1, the eigenvectors are returned.
'
'Output parameters:
'    D       -   eigenvalues in ascending order.
'                Array whose index ranges within [1..N].
'    Z       -   if ZNeeded is equal to:
'                 * 0, Z hasn’t changed;
'                 * 1, Z contains the eigenvectors.
'                Array whose indexes range within [1..N, 1..N].
'                The eigenvectors are stored in the matrix columns.
'
'Result:
'    True, if the algorithm has converged.
'    False, if the algorithm hasn't converged (uncommon case).
'
'  -- ALGLIB --
'     Copyright 2005 by Bochkanov Sergey
'
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Public Function SymmetricEVD(ByRef A_() As Double, _
         ByVal N As Long, _
         ByVal ZNeeded As Long, _
         ByVal IsUpper As Boolean, _
         ByRef D() As Double, _
         ByRef Z() As Double) As Boolean
    Dim Result As Boolean
    Dim A() As Double
    Dim Tau() As Double
    Dim E() As Double
    A = A_
 
    Call ToTridiagonal(A, N, IsUpper, Tau, D, E)
    If ZNeeded = 1# Then
        Call UnpackQFromTridiagonal(A, N, IsUpper, Tau, Z)
    End If
    Result = TridiagonalEVD(D, E, N, ZNeeded, Z)
 
    SymmetricEVD = Result
End Function

i got this module from http://www.alglib.net/eigen/symmetric/symmevd.php .. i have add the ap lib module and this module...

i used that code to test the function SymmetricEVD

Private Sub Command1_Click()
Dim mat(0 To 1, 0 To 1), Result(0 To 1, 0 To 1), eigenvect(0 To 1, 0 To 1) As Double
 
mat(0, 0) = 1
mat(0, 1) = 2
mat(1, 0) = 3
mat(1, 1) = 4
 
Call SymmetricEVD(mat, 2, 1, True, Result, eigenvect)
End Sub

but i get "type mismatch"

[Grimfort]

It would, you have a multi-dimension array being passed to a function that only takes an array

ie:

SymmetricEVD(ByRef A_() As Double Needs a Dim mat (0 to 1) not a mat(0 to 1, 0 to 1). What makes you think you had to do that?

[lplover2k]

in the module description
"symmetric matrix which is given by its upper or lower
' triangular part.
' Array whose indexes range within [1..N, 1..N]."
how can i store a matrix in a 1d array??

[Grimfort]

The function should read like this if that was the case, but I have no idea what the functions you are calling within that are declared as:

Public Function SymmetricEVD(ByRef A_(,) As Double, _
ByVal N As Long, _
ByVal ZNeeded As Long, _
ByVal IsUpper As Boolean, _
ByRef D(,) As Double, _
ByRef Z(,) As Double) As Boolean

[Grimfort]

I've just read the site (Im feeling helpful ) the code you are using is from VB6, which you do not have to declare as a specifc array size. You can use either (0 to 1) or (0 to 1, 0 to 1).

[lplover2k]

oh i posted in the wrong forum.. but anyway how can i use this in vb 2005??

[Grimfort]

It depends what you have, I assume you have a .dll from this place that contains UnpackQFromTridiagonal and TridiagonalEVD methods?

[lplover2k]

no it's not a .dll but a .bas for the other functions

[Grimfort]

Well, you will have to convert them as well into a module, and update it to take the new array, probly in the method declaration again.

[lplover2k]

anyway what am i doing wrong in my code..cuz i am getting "type mismatch"

[Grimfort]

I have already said what would be going wrong, and suggested what to do.

You need to convert the bas file into .net. You will most likely have to change the .bas file to use this array, as VB6 allows you to pass arrays about without being specific of their size. This will mean changing the declaration of the functions to use multi-dimension arrays.

I have included an example of what the new function header would look like, but you havent shown anything of the .bas file so I can't advise on how to change it.

[lplover2k]

oh ok will post this on vb6 forum thanks

[Grimfort]

Im lost, I thought you are coding this in .net 2005 ?

[Grimfort]

It all becomes clear...
It is VB6 your using this in, which works differently. But you did ask how to get this working in 2005. Sorry for wasting your time.