Lab 2

Lab 1VBA PROGRAMMING IN EXCEL 2007

Dr. Majid Mohammadianmajid.mohammadian@uottawa.ca

Adding the Developer Tab  Click the Microsoft Office Button: and then click Excel Options.Click Popular, and then select the Show

Developer tab in the Ribbon check box.

MACRO SECURITYExcel has several levels of Macro Security that

can be selected using Developer Macro Security

Select Enable all You can also create a self-signing

certificate

OPENING VBA EDITOR IN EXCEL 2007Two ways to access the excel VBA

programming environment:Alt F11Using the Developer tab Visual Basic

THE PROGRAMING ENVIRONMENT

Project ManagerEditor

Properties

ADDING A NEW MODULESelect your spreadsheet in the project

explorerUse the main menu or the contextual menu

(mouse right button) to insert the new module

A simple function: my_sumOpen VBA using alt+f11Type the following:

Function my_sum(a, b) my_sum = a + bEnd Function

Return to excel using Alt+qUse your functionSave your file as Macro-Enabled (*.xlsm )

Single and double precisionAdd the following functions

Function test_s()Dim x As Singlex = 1.23456789012345test_s = xEnd Function

Function test_d()Dim x As Doublex = 1.23456789012345test_d = xEnd Function

Analytical solution:

Numerical (finite difference) solution:

We are going to implement both solutions in Excel

( ) 1 c m tgmv t ec

1 1( ) ( ) ( ) ( )

orNew value Old value slope step size

i i i i icv t v t g v t t tm

THE PARACHUTIST PROBLEM

ANALYTICAL SOLUTIONTo calculate analytical solution using

Excel, let us first set up a simple spreadsheet. As shown below, the first step involves entering labels and numbers into the spreadsheet cells

To attach names to parameters values, select cells Formula tab Define Name

Create the time column: D8=0D9=D8+dt, Drag down

Type the following formula in F8=g*m/cd*(1-exp(-cd/m*D8))Drag down

Numerical: G8=0: (Type in G9) =G8+(g-cd/m*G8)*dt

Function v2_parachute

Function v2_parachute(v1, dt, g, cd, m)v2_parachute = v1 + (g - cd / m * v1) * dtEnd Function

MACHINE EPSILONMachine, or computer epsilon (eps) is the smallest

floating point number that can be added to a floating point 1 that yields a result different from 1.

It is determined by the following type of algorithmepsi=1DOIF(epsi+1 < 1 ) EXITepsi = epsi / 2

END DOepsi = epsi * 2print epsi

END

VBA CODE FOR MACHINE EPSILON

Function machineeps()Dim epsi As Doubleepsi = 1DoIf 1 + epsi <= 1 Then Exit Do epsi = epsi / 2Loopmachineeps = 2 * epsiEnd Function

Single precisionFunction machineeps_s()Dim epsi As Singleepsi = 1DoIf 1 + epsi <= 1 Then Exit Do epsi = epsi / 2Loopmachineeps_s = 2 * epsiEnd Function

Other TasksTask 6: Create a table where x are the values from -3.1415 to 3.1415, and the values of y are y= cos(x) without using VB. Plot it. Add a title “y= cos (x)”, the axis titles x and y, and the legend. Now add another column with values of y=sin(x). Try to add the new series of values to the plot without plot the graph again (Hint: See “Adding a new series of values” in Plotting ). Note: Give your function in VB a special name e.g. my_cos (why?).

Task 7: Define the function y= cos(x) +sin(x) using VB, and plot it from 0 to 3.1415.

Task 8 (To be submitted with assignment 2): Write a VBA code for the falling parachute problem assuming that the drag force formula is now FD is now FD=cV2. Submit a print of all your VBA procedures and a table of v versus t using the following data: c =0.125kg/s and