matrix calculations

Hi,

I know to use Excel - matric on cells but how can I define dynamic matrix, inverse, transposed?


In fact I have data always in a different number of rows and array.

How can I define the main matrix, its inverse, transpose, inverse, multiplication?

Thanks a lot,

I know that it might be a bit hard, but I can explain much more in details.

Regards

A_2008

Hi Angelo2008 and welcome to the forum! :)

Please be sure to read the posting guidelines (http://www.xtremevbtalk.com/faq.php?faq=evbf_faq#faq_evbf_rules).


Can you give us a bit more detail on what you're after here? A little background and your final goal would be helpful. If you're asking what I think you're asking then I think you're going to have to use VBA.

I take it that you are already familiar with worksheet functions such as MINVERSE, MMULT, MDETERM and TRANSPOSE?

Colin

Hi Colin

Thanks a lot,
First of all, yes, I am familiar with worksheet functions such as MINVERSE, MMULT, MDETERM and TRANSPOSE, but only in the case I manipulate them within a worksheet.


so what is my goal?: Get data from a txt or csv file, then import it ??
to locate the length of data ( m lines) ??
==> I do it: finding estimators
build a first matrix called J ( n columns, m lines) ???
building an other matrix based on
[(Jtranspose * J)^(-1)*Jtranspose ] = H ???
building up a loop such [ that H* array ] provide a vector

and do [H* array ] *[new vector]

until the consecutive new vectors after a loop remain similar at 1% or 0.05 %


In fact it is the Levenberg-Marquard method's shown on wikipedia, but without the dampimg factor.

This is the goal, but as data are never similar in number of lines , automation is better and faster than manually, even if I start from very close values.

Thanks a lot,

Angelo2008

Hi Angelo2008,

Which version of Visual Basic are you going to be working with? Excel VBA? VB6? VB .Net?

And which part of the process are you having the difficulty with? Importing the file? Determining the size of the matrix?

Note that you can access many worksheet functions from Excel VBA using the application object's worksheetfunction property.

Matrix operations in VBA are straightforward, and the familiar worksheet functions are available. A difference is that some of the things that you can do in array formulas (like adding or multiplying a scalar and an array) don't work in VBA -- but there are workarounds.

If you can provide more information, I'd be happy to help.