It looks like you're new here. If you want to get involved, click one of these buttons!

- 140.3K All Categories
- 104.2K Programming Languages
- 6.3K Assembler Developer
- 1.8K Basic
- 39.7K C and C++
- 4.2K C#
- 7.9K Delphi and Kylix
- 3 Haskell
- 9.6K Java
- 4.1K Pascal
- 1.3K Perl
- 1.9K PHP
- 502 Python
- 47 Ruby
- 4.3K VB.NET
- 1.6K VBA
- 20.8K Visual Basic
- 2.6K Game programming
- 308 Console programming
- 88 DirectX Game dev
- 1 Minecraft
- 108 Newbie Game Programmers
- 2 Oculus Rift
- 8.9K Applications
- 1.8K Computer Graphics
- 726 Computer Hardware
- 3.4K Database & SQL
- 519 Electronics development
- 1.6K Matlab
- 627 Sound & Music
- 253 XML Development
- 3.2K Classifieds
- 189 Co-operative Projects
- 169 For sale
- 189 FreeLance Software City
- 1.9K Jobs Available
- 598 Jobs Wanted
- 196 Wanted
- 2.9K Microsoft .NET
- 1.7K ASP.NET
- 1.1K .NET General
- 2.9K Miscellaneous
- 3 Join the Team
- 2 User Profiles
- 352 Comments on this site
- 56 Computer Emulators
- 1.7K General programming
- 136 New programming languages
- 598 Off topic board
- 156 Mobile & Wireless
- 30 Android
- 124 Palm Pilot
- 334 Multimedia
- 151 Demo programming
- 183 MP3 programming
- 0 Bash scripts
- 15 Cloud Computing
- 52 FreeBSD
- 1.7K LINUX programming
- 363 MS-DOS
- 0 Shell scripting
- 318 Windows CE & Pocket PC
- 4.1K Windows programming
- 876 Software Development
- 401 Algorithms
- 67 Object Orientation
- 81 Project Management
- 88 Quality & Testing
- 232 Security
- 7.5K WEB-Development
- 1.8K Active Server Pages
- 61 AJAX
- 2 Bootstrap Themes
- 55 CGI Development
- 19 ColdFusion
- 221 Flash development
- 1.4K HTML & WEB-Design
- 1.4K Internet Development
- 2.2K JavaScript
- 33 JQuery
- 282 WEB Servers
- 107 WEB-Services / SOAP

Welcome to the new platform of Programmer's Heaven! We apologize for the inconvenience caused, if you visited us from a broken link of the previous version. The main reason to move to a new platform is to provide more effective and collaborative experience to you all. Please feel free to experience the new platform and use its exciting features. Contact us for any issue that you need to get clarified. We are more than happy to help you.

blankablanka
Posts: **2**Member

in VBA

Could anyone help me with the following problem:

Write a VBA function that computes one real-valued root of the polynomial defined by

P(x) = (summation mark from i=1 to n) coeffs.cells(i,1) x^(powers.cells(i,1))

where n=coeffs.Rows.Count using Newton's Solver. For the input, coeffs is a Range with n rows (and 1

column) of real-valued coefficientcients, and powers is a Range with n rows (and 1 column) of non-negative,

integer powers.

I guess ''Newton's Solver'' is actually the Newton-Raphson algorithmn.

My solution so far is:

Function polySolver(coeffs As Range, powers As Range) As Double

Dim rowCount As Integer

Dim i As Integer

Dim xn As Double

Dim xnm1 As Double

Dim fx As Double

fx = 0

Dim fxprime As Double

fxprime = 0

xnm1 = 0.1

rowCount = coeffs.Rows.count

Do

For i = 1 To rowCount

fx = fx + coeffs.Cells(i, 1) * xnm1 ^ powers.Cells(i, 1)

fxprime = fxprime + (powers.Cells(i, 1) * coeffs.Cells(i, 1)) * xnm1 ^ _

(powers.Cells(i, 1) - 1)

Next i

xn = xnm1 - fx / fxprime

xnm1 = xn

Loop Until (Abs(fx) < 0.00001)

polySolver = xn

End Function

When I choose different initial values of x0 (in the code denoted with xnm1), I get different solutions. This function probably shouldn't even contain the initial x0 (I suppose that the should't have an assigned value for xnm1). The algorithmn should be valid for any polynomial and the outcome should be one real-valued root of this polynomial.

I will be extremely thankful for any advice you can offer me!

Write a VBA function that computes one real-valued root of the polynomial defined by

P(x) = (summation mark from i=1 to n) coeffs.cells(i,1) x^(powers.cells(i,1))

where n=coeffs.Rows.Count using Newton's Solver. For the input, coeffs is a Range with n rows (and 1

column) of real-valued coefficientcients, and powers is a Range with n rows (and 1 column) of non-negative,

integer powers.

I guess ''Newton's Solver'' is actually the Newton-Raphson algorithmn.

My solution so far is:

Function polySolver(coeffs As Range, powers As Range) As Double

Dim rowCount As Integer

Dim i As Integer

Dim xn As Double

Dim xnm1 As Double

Dim fx As Double

fx = 0

Dim fxprime As Double

fxprime = 0

xnm1 = 0.1

rowCount = coeffs.Rows.count

Do

For i = 1 To rowCount

fx = fx + coeffs.Cells(i, 1) * xnm1 ^ powers.Cells(i, 1)

fxprime = fxprime + (powers.Cells(i, 1) * coeffs.Cells(i, 1)) * xnm1 ^ _

(powers.Cells(i, 1) - 1)

Next i

xn = xnm1 - fx / fxprime

xnm1 = xn

Loop Until (Abs(fx) < 0.00001)

polySolver = xn

End Function

When I choose different initial values of x0 (in the code denoted with xnm1), I get different solutions. This function probably shouldn't even contain the initial x0 (I suppose that the should't have an assigned value for xnm1). The algorithmn should be valid for any polynomial and the outcome should be one real-valued root of this polynomial.

I will be extremely thankful for any advice you can offer me!

About & Contact / Terms of use / Privacy statement / Publisher: Lars Hagelin

Programmers Heaven articles / Programmers Heaven files / Programmers Heaven uploaded content / Programmers Heaven C Sharp ebook / Operated by CommunityHeaven LLC

© 1997-2013 Programmersheaven.com - All rights reserved.