Scientific programming using Excel VBA for beginners

Scientific Programming Using
Excel VBA for Beginners
Dr. RIZAuddin bin Saian
Faculty of Computer & Mathematical Sciences
Universiti Teknologi MARA (Perlis)
Venue: LT1, UiTM Perlis
27 September 2019 (Friday)
3pm

Problem
• We want to find the root for .
227/09/2019 Scientific Programming Using Excel VBA ::: rizauddin.com

Objective
• To approximate the root for
using Newton’s method (Newton-Raphson
method)
– Perform Newton’s method by hand.
– Write a VBA code to perform the Newton’s
method.

Newton’s Method

Equation of tangent line

Initial Guess of x
6
Actual root
X
X
x0
(Initial guess)

Iteration 1
7
X
Tangent line at x0 = -1
X
x0x1
Actual root
(Initial guess)

Iteration 2
8
x1
Tangent line at x1
X X
x0
Actual root
(Initial guess)

Example: Find the root.
9
Actual root
X
x0 = -1
X

Initial guess of x
10
The estimated root,

Iteration 1
11
i x xn+1
0 - 1 -1.5

Iteration 2
12
i x xn+1
0 - 1 -1.5
1 -1.5 -1.347826087

Iteration 3
13
i x xn+1
0 - 1 -1.5
1 -1.5 -1.347826087
2 -1.347826087 -1.325200399

Iteration 4
14
i x xn+1
0 - 1 -1.5
1 -1.5 -1.347826087
2 -1.347826087 -1.325200399
3 -1.325200399 -1.324718174

Iteration 5
15
i x xn+1
0 - 1 -1.5
1 -1.5 -1.347826087
2 -1.347826087 -1.325200399
3 -1.325200399 -1.324718174
4 -1.324718174 -1.324717957

Iteration 6
16
i x xn+1
0 - 1 -1.5
1 -1.5 -1.347826087
2 -1.347826087 -1.325200399
3 -1.325200399 -1.324718174
4 -1.324718174 -1.324717957
5 -1.324717957 -1.324717957

Iteration 6
17
i x xn+1
0 - 1 -1.5
1 -1.5 -1.347826087
2 -1.347826087 -1.325200399
3 -1.325200399 -1.324718174
4 -1.324718174 -1.324717957
5 -1.324717957 -1.324717957
STOP!

Visual Basic for Application (VBA)
18
Press Alt key and hold. Then, press F11 together to open the VBA Editor.

Add new Module

Define a function

Exercise 1
• Define function Newton with parameter “x”
and return the estimation value for the root
of with x0=-1.

Loop

Exercise 2
• Modify the Newton function in Ex. 1 to use
loop to calculate the root using 4 iterations.

THANK YOU
www.rizauddin.com
27/09/2019 Scientific Programming Using Excel VBA ::: rizauddin.com 26

Scientific programming using Excel VBA for beginners

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