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Names: »LESSON2.PC«
└─⟦a6ed1cd35⟧ Bits:30002862 Perfect Calc 1.10 for JET80 CP/M
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>a2:" LESSON2 -- Entering Data
>a4:" In this lesson we will practice entering data in the Stock
>a5:" Portfolio spreadsheet, (filename 'b:stockex.pc'), which we use in
>a6:" Lesson 1. This spreadsheet already contains some data--
>a7:" labels, numbers, and formulas--but let us practice adding more,
>a8:" beginning with numbers.
>a9:" Let us begin by splitting the screen and calling up the 'stockex.pc'
>a10:" file. Move the cursor to line 11 (the indicator in the lower right edge
>a11:" of the screen should read 'a11' when you're there) and enter the
>a12:" CREATE TWO WINDOWS Command:
>a13:" Control--x 2
>a14:" ÆAnswer 'n' for "no", to the prompt "Sychronize windows?"Å
>a15:" Next move the cursor into the other ÆtopÅ window using:
>a16:" Control--x o (the letter 'o')
>a17:" Use the 'Other Window' commands learned in the first lesson to
>a18:" scroll the bottom window:
>a19:" FORWARD: Control--x Control--v
>a20:" BACKWARD: Control--x Control--z
>a21:" Call up the 'stockex.pc' file. Enter the FIND FILE Command:
>a22:" Control--x Control--f
>a23:" When Perfect Calc responds, "File to Find <CR>: " enter the filename:
>a24:" 'b:stockex.pc', followed by a carriage return.
>a26:" NUMBERS
>a27:" Perfect Calc distinguishes a number from a label or a formula, by
>a28:" the first character that you type. That is, if the first character is
>a29:" a ' - ' (hyphen, or minus sign), a ' . ' (period, or decimal point),
>a30:" or any digit, 0 - 9, Perfect Calc assumes you are entering a number.
>a32:" Using an appropriate cursor command or arrow key, move the cursor
>a33:" to position 'c6' and type a value for the current price of Xerox stock,
>a34:" e.g. $40. Type the number '40' (omitting the dollar sign) and hit
>a35:" 'Enter' or 'Return'. (Use the DELete key to erase typing errors.)
>a36:" At the first digit Perfect Calc displays the message "Number:"
>a37:" in the Prompt Line. The number you type appears initially following
>a38:" this message. It will not be entered into the spreadsheet until
>a39:" you type 'Enter' or 'Return'.
>a40:" After you hit the 'Return' key, Perfect Calc enters the number
>a41:" and recalculates the spreadsheet, displaying a value of '8000' for
>a42:" 'Current Value', position 'e6'.
>a43:" Notice that numbers are displayed showing two decimal places,
>a44:" which is Perfect Calc's default display notation. In Lesson 6 we
>a45:" will see how this can be changed.
>a47:" FORMULAS
>a48:" Formulas express the relationships that exist among the data
>a49:" held in your spreadsheet. For example, a formula for your home
>a50:" 'expenses' might be: Expenses = Rent + Utilities + Food. In general,
>a51:" formulas consist of numbers, variables, arithmetic operators, and/or
>a52:" functions. Arithmetic operators are the common symbols of arithmetic
>a53:" that we are all familiar with:
>a55:" ^ To the power of (e.g. 3^2 means "3 to the power of 2",
>a56:" or 'three squared' or 3 x 3 = 9)
>a57:" * Multiplication
>a58:" / Division
>a59:" + Addition
>a60:" - Subtraction
>a61:" Move the cursor to position 'e6', which records the 'Current
>a62:" Value' of the Xerox stock. The formula for this position, as displayed
>a63:" in the Prompt Line, instructs Perfect Calc to multiply ( * ) whatever
>a64:" value is contained in position 'b6' ('Number of Shares') by whatever
>a65:" value is held in position 'c6' ('Current Price'). This result is then
>a66:" displayed in position 'e6' ('Current Value').
>a67:" As you can see, only the value which the formula computes displays
>a68:" on the spreadsheet, while the formula itself ÆFormula: b6 * c6Å
>a69:" displays in the Prompt Line, and then ONLY when the cursor is occupying
>a70:" the entry position that contains it.
>a71:" Let us enter a formula. Move the cursor to position 'f6', which
>a72:" records 'Percentage Gain/Loss'. This entry position will hold a
>a73:" formula that will compute the percentage we have gained or lost on
>a74:" our investment in this stock. The formula will be:
>a76:" f6 = (c6 - d6) / d6
>a78:" This instructs Perfect Calc to subtract the Purchase Price from
>a79:" the Current Price, and to divide the result by the Purchase Price.
>a80:" The result will be displayed in position 'f6'.
>a81:" With the cursor at position 'f6' type an equals sign ( = ).
>a82:" This tells Perfect Calc that you wish to enter a formula for this
>a83:" position. Start typing the formula now. Again, it will be:
>a85:" FORMULA: f6= (c6 - d6) / d6
>a87:" Blanks are ignored by Perfect Calc and so may be inserted
>a88:" for readability. If you make a mistake, use the DELete Key to backup
>a89:" and retype. As you did with numbers, type the formula at the prompt
>a90:" line and then enter it onto the spreadsheet with a carriage return.
>a91:" Perfect Calc recalculates the spreadsheet displaying a result
>a92:" of '-0.20' in position 'f6', indicating that a loss of 20 percent has
>a93:" occurred for this stock. Actually, percentages should be displayed
>a94:" as whole numbers, not as decimal fractions. Let us change the formula
>a95:" so that it will do this.
>a96:" Perfect Calc provides a very convenient method of changing
>a97:" a formula (or label) entry, which does not require retyping the entire
>a98:" entry. Called the EDIT ENTRY Command, it cause the formula which the
>a99:" cursor is occupying to be displayed in the Prompt Line, where you
>a100:" you may change it however you wish. To help you, Perfect Calc
>a101:" modifies several of its commands:
>a103:" Control--a Moves Cursor to BEGINNING of Prompt Line
>a104:" Control--e Moves cursor to END of Prompt Line
>a105:" Control--f Moves Cursor FORWARD one character
>a106:" Control--b Moves Cursor BACKWARD one character
>a107:" Control--d DELETES character occupied by the cursor
>a108:" DEL Key DELETES characters backward
>a109:" Control--g CANCELS changes made & returns to original formula
>a110:" Return key Enters the modified formula.
>a111:" At this time, with the cursor on position 'f6' type the EDIT
>a112:" ENTRY Command:
>a113:" Control--x e
>a114:" Perfect Calc responds by displaying the formula in the Prompt Line:
>a115:" EDIT: (c6 - d6) / d6
>a116:" Using the above editing commands, change the formula to read:
>a118:" f6 = ((c6 - d6) / d6) * 100
>a119:" When you have finished, enter the modified formula into the
>a120:" spreadsheet using a carriage return. Perfect Calc automatically
>a121:" recalculates the spreadsheet, displaying a new value of '-20.00' in
>a122:" entry position 'f6'.
>a124:" FUNCTIONS
>a125:" Now let us consider a formula containing a simple function. A
>a126:" function is a kind of pre-structured formula which performs a
>a127:" mathematical operation, and which would be difficult or time consuming
>a128:" to structure ourselves. Functions perform such operations as computing
>a129:" sums, averages, square root, and so forth.
>a130:" Move the cursor to position 'e18', the entry which will compute
>a131:" 'Current Equity'. This figure, which is the sum of all values in
>a132:" column 'e', will represent the total current worth of the stocks we
>a133:" own. Presently, we have only one stock, Xerox, showing a total current
>a134:" value of $8000. However, in a few moments we will be adding stock for
>a135:" other companies into lines 6 through 15. We could write our formula
>a136:" as follows:
>a137:" e18 = e6 + e7 + e8 + e9 + e10 + e11 + e12 + e13 + e14 + e15
>a138:" This would give us the correct total. However, it is an awkward
>a139:" formula, and if we add more than 8 stocks, we will have to rewrite it.
>a140:" Perfect Calc provides an answer with its 'sum' function, which
>a141:" will compute the sum of variables over a 'range'. A range is simply
>a142:" any continuous series of entry postions, whether in a line, a column,
>a143:" or a rectangular area of both lines and columns. The entry positions
>a144:" 'e6' through 'e15' represent a columnar range of values. Using the
>a145:" sum function we can write our formula very concisely, as follows:
>a146:" e18 = sum(e6:e15)
>a147:" Notice that the range is enclosed in parentheses and follows right
>a148:" after the function name, leaving no blank space. As well, the range is
>a149:" specified by the first and last entry positions, separated by a colon.
>a151:" Enter this formula into entry position 'e18':
>a152:" FORMULA: e18=sum(e6:e15)
>a153:" Use the equal sign '=' to start the formula entry. This entry recalcu-
>a154:" lates the spreadsheet displaying a value of $8000 for 'Current Equity'.
>a156:" Perfect Calc provides a large number of built-in functions similar
>a157:" to the 'sum' function. These include virtually all of the built-in
>a158:" functions found on other electronic spreadsheet programs. However, as
>a159:" we will learn in lesson8, it is possible to build a 'user-extendable'
>a160:" functions library which makes the number of functions available
>a161:" virtually limitless. Let us examine the current built-in functions
>a162:" listed in the Help Menu:
>a163:" Type Help: ? and select '5'.
>a164:" NOTE: To return to these instructions scroll the bottom window using:
>a165:" Control--x Control--v
>a172:" LABELS
>a174:" The last type of data entry we will examine are labels. Labels
>a175:" are those words and symbols in the spreadsheet that identify the
>a176:" various lines, columns, and entry positions. At present there are more
>a177:" labels on our spreadsheet than numbers and formulas. Labels make
>a178:" the spreadsheet not only easy to use but also aesthetically pleasing
>a179:" to view. No computations are performed on labels.
>a181:" Any printable character which does not begin a command, a number
>a182:" or a formula may begin a label. However, should it happen that a label
>a183:" must begin with, for example, a hyphen, an equals sign, or a period,
>a184:" which would otherwise signal a number or a formula, the label can be
>a185:" 'forced' by typing a double quote ( " ) before beginning the label.
>a187:" Move the cursor to entry position 'a7' and type the label 'IBM'.
>a188:" As with numbers and formulas, the label is displayed initially in the
>a189:" Prompt Line following the message: "LABEL: ". Instead of entering
>a190:" the label with the return key, use the FORWARD Command (Control--F).
>a192:" Notice that Perfect Calc enters the label, and then moves the
>a193:" cursor right one column position, where it is ready to receive a
>a194:" numeric value for 'Number of Shares'.
>a196:" Make up and enter sample numbers for IBM stock. Each time a number
>a197:" is entered, Perfect Calc recalculates the spreadsheet. When you have
>a198:" finished with IBM, enter stock holdings for other companies, such as
>a199:" General Motors, Bank of America, Georgia Pacific, etc.
>a201:" Once the data has been entered, change the 'Current Price' for
>a202:" various stock, observing how Perfect Calc automatically recalculates
>a203:" the current value of your stock holdings, your percentage gain or loss
>a204:" for each, and your current equity.
>a206:" THIS is the power of Perfect Calc!
>a208:" When you have finished, and if you wish to continue to the next
>a209:" lesson, which deals with storing and printing the spreadsheet, simply
>a210:" clear the entire memory and read in the 'lesson3.pc' file.
>a211:" The CLEAR ENTIRE MEMORY Command is: Control--x Control--k
>a213:" The FIND FILE Command is: Control--x Control--f
>a215:" If you do not wish to continue with the lessons now, type the
>a216:" QUIT Command:
>a217:" Control--x Control--c
>a218:" Answer 'y' for yes to Perfect Calc's question: "Ignore changes
>a219:" this session?"
>a220:" END OF LESSON 2
>a1
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