Introduction to Chemical Engineering Computing

•  Circle all answers that are correct; there can be 0 to 5 correct answers. Which of the statements below is true?

A subroutine cannot open a message box
A subroutine can only return ONE value to an open spreadsheet
A subroutine can insert a new spreadsheet
A subroutine cannot use a function
A subroutine can use either a function and/or another subroutine

•  Which of the statements below is false regarding Macro Recording?

The macro recorder creates a subroutine that can format a table
The macro recorder creates a function that generates a plot in an open worksheet
The macro recorder creates VBA code that can calculate a formula by using values from a spreadsheet
The macro recorder creates VBA code for a user-defined function within a subroutine

•   If the VBA code below was complete, what is the value of TodaysValue assuming k =8?Show the calculation the computer would do.

Dim Values(1 To 10, 1 To 10) As Single
For i = 1 To 10
For j = 1 To 10
Values(i, j) = (i+50) / (k * j)
Next j
Next i

TodaysValue = Values(3, 2)

After the code has executed what is the value of the variable TodaysValue?
TodaysValue = __________

• Programming Exercises

Using Sheet1 of your Excel workbook, write a user defined function with an If ...ElseIf...Else...End If statement to evaluate the following function, y(x):
( x≤-1: y=cos?(sin?(x) )@-10: y=cos?(x) )
Use your user defined function to plot y(x) from x=-5 to x=5.

Problem 2

On Sheet2 of your workbook, find the number of real roots of the following polynomial using a user defined function:
y(x)=0.001x^6-0.04x^5+0.23x^4-1.15x^3+1.1x^2-3.05x-55.2
Remembering that the number of real roots equals the number of times the polynomial crosses the x-axis, find the roots by plotting the polynomial on the interval -10≤x≤10. List the number and approximate value of the roots you find:
Number of real roots = _________________________
Approximate value of roots = ______________________________________________

Problem 3

The Maclaurin series for the inverse hyperbolic tangent is given by
?tanh?^(-1) (x)=∑_(n=1)^∞¦1/(2n-1) x^(2n-1)
Using Sheet3 of your workbook, create a UserForm that allows the user to
Choose the option to write the nth term of the series on the worksheet
Choose the option to write the sum of the first n-terms on the worksheet
Make the OKCommandButton and theOptionButton for the sum of the n-terms as the default buttons
Create a button on the spreadsheet that starts the UserForm
For x=0.42 use your program on Sheet3 to calculate:
The value of the 10th term in the series: ____________________
The sum of the first 10 terms in the series: ___________________