by JOHN G. RONCZ, EAA 112811 15450 Hunting Ridge Tr. Granger, IN 46530-9093

More we go on to the next topic, I'd like to take this opportunity to answer some of the questions which EAA members have written to me about over the course of the first four articles. Several members don't understand the symbols I've been using. Everyone understands + and -, which are addition and subtraction. The asterisk * means multiplication, and the slash / means division. The carat or up-arrow " means to raise the number to a power. For example, 2"3 means to take the

same as taking its square root, so 4".5 gives the answer 2. The symbol < means "less than", and the symbol > means "greater than". I should have explained this computer notation sooner, so forgive me. Some EAA members are having trouble converting the formulas from Lotus 1-2-3 or Excel to other spreadsheet formats. I can't help you beyond explaining the functions I've been using. Think of a spreadsheet function as inter-office mail. You put the function name on the outside of the envelope, and you put some instructions inside the envelope. Your secretary routes the mail to the appropriate department, which is the same as the function name. Later, the function department sends back to you a single number, which represents the answer you wanted. Spreadsheet functions use parentheses ( ) to indicate what's inside the envelope. The functions we've used are (in Lotus 1-2-3 form): • (" SQRT(x): This department calculates the square root of whatever number is inside the parentheses. If you put 4 inside the parentheses, you'd get the number 2 back. If your spreadsheet

number 2 and raise it to the third power, which gives the answer 8. Raising any number to the one-half power is the

doesn't support this function, then use x".5, which gives the same answer. returns an approximation to

There is an error in the weight and balance spreadsheet published with my article in the May 1990 issue. The formula in cell B28 should read E28/C28, instead of E28/D28. The error is in the calculation of the vertical position of the center of gravity. The error occurred when the spreadsheet was converted from 1 2-3 to Excel Format. Sorry I didn't catch the error at the time.

the value of pi, or 3.14159. There is nothing inside the parentheses because the («.'PI department isn't too bright and only knows one number. • (n EXP(x): This department takes the number e and raises it to whatever power you put inside the parentheses. Since eis approximately 2.71828183, if you wanted (« EXP(3.5), for example, you could get the same answer by using 2.71828183"3.5.

9 (fi \F(condition, formulal, formula^. The ability to make decisions is what separates computers from calculators. Spreadsheets, therefore, have a way of letting the computer make a decision based upon the information you give it. The («IF department first evaluates the condition you specified. If the condition is true, then it calculates a number using formulal, and sends it back to you. If the condition is false, then it uses formula2 to calculate the answer, and sends that number back to you. For example, C« IF(2