3. In our Iteration sub, we are doing a fixed number of iterations (.e., n llerations- no more, no less). Sometimes,

our ferative process may require fewer iterations or more iterations and we want to make sure that our sub can

be adaptable.

Now, we are going to adapt our Iteration sub such that it will keep iterating until a certain tolerance is met. The

flowchart for this is shown on the next page.

CHEN 1310

BIO

begin

inputx

Lab 900

Tel-0.001

xnew-x)

Er-x-

E

Tol?

And the code for this new flowchart is shown here:

xxnow

Loop Until Err Pol

MogBox FormatNumber (3)

End Sub

option Explicit

Sub Iteration ()

Din xinit As Double, x As Double

Din Err As Double, Tol As Double, new As Double

xinit InputBox("Please enter initial guess.")

x-xinit

701 = 0.001

Do

xnow = sqr(x (1/3) + 5*x)

Err- Abs (xnew- x)

output x

and

Page 3

Adapt your code to that shown above. Notice that we have a Do...Loop Until in which we calculate an error

(Err) and compare it to a tolerance (Tol). Tol is a value that can be set by the user-we iterate until (and hence

the Loop Until)-the difference between subsequent x-values is less than or equal to Tol. Note that we also

need to add Dim statements for Err, Tol, and xnew. We have eliminated in and I and the Dim statements for

n and I because they are no longer needed. Now would be a good time to save!/nStep through (using FB) your code to make sure it is working. Enter 4 as the initial guess. You should have

gotten the same answer as you did before using a fixed number of iterations.

The code is a bit more involved, but why do you think implementing the loop might be more advantageous than

a fixed number of terations?

CHEN 1310

Lab 905

Page 4

What is the significance of xnew? In other words, why do we need to define xnew as a separate variable?