ENGG1811 Computing in Engineering ENGG1811 Computing for Engineers Analysis Computing systems Modelling are pervasive, but and management of they have a special often huge data sets real or planned Computing in Engineering role in engineering, systems climate trends, – Making effective use of technology in analysis and such as these climate, structures, astronomy, mining, design application areas geological processes, materials, … Spreadsheet Concepts nuclear fusion, … – History and rationale Tools Automating – Key concepts supporting good engineering design – Number representation and limits The engineer’s tedious, dangerous or precision tasks – Charts CAD, spreadsheets, goal: improve – Organising data: visualisation tools, living standards remote monitoring, sorting and filtering project and resource microsurgery , – Useful functions and features management comms, radiography, energy supply, … ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 1 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 2 Spreadsheet Prehistory Prehistory, continued π • Engineers and scientists have been solving problems for many ≈ 792.0 ≈ (89.0 exact .0 88622 K) A linear slide rule example: 4 decades, indeed millennia. Until the availability of electronic calculators π their main tools were pen, paper, and slide rule 1. Align on main scale with 4 on • Slide rules are sophisticated analogue calculating devices. They can red division scale perform multiplication, division, roots, and some trigonometry. Technology is based on logarithms: a ×b = antilog(lo g a + log b) Multiplication just aligns two log scales. Circular slide rule example 2. Read off intermediate (6.35 × 7.0 = 44.45) 3. Realign scales and 2. Move cursor to b value, a bit more use cursor against on inner scale, read than 0.79 square root scale answer on outer scale 1. Point Then came 4-function calculators in the early 1970s, inner scale index to a then scientific calculators, then programmable scientific calculators (500 steps, 100 memory locations), then personal computers…. ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 3 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 4 New tools: VisiCalc, Lotus and Excel Lotus 1-2-3 In 1978 Dan Bricklin and Bob Frankston of Mitch Kapor , a VisiCalc product Harvard Business School (shown here in 1980, manager and programmer, saw the left to right) invented VisiCalc for the Apple II. potential of the spreadsheet as a killer app for the IBM-PC. VisiCalc was the first electronic spreadsheet, which they sold at computer shows for $100 He and programmer Jonathan Sachs, per disk. developed a better product called Lotus 1-2-3, and founded the Lotus Corporation (now part of IBM). The product was a runaway success, References : http://dssresources.com/history/sshistory.html with sales topping US$53 million in the http://en.wikipedia.org/wiki/Image:VisiCalc_%28IBM first year (1983) _PC%27s_Killer_Application%29.PNG ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 5 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 6 ENGG1811 Spreadsheets 1 ENGG1811 Microsoft Excel Why Use a Spreadsheet? In the meantime Bill Gates had founded Microsoft, and Excel was written for the Many things that can be done with a pencil, a pad of paper, and a calculator 250K Apple Macintosh in 1985 can be done much faster, far more accurately and conveniently using a spreadsheet. It had the graphical The biggest advantage of using spreadsheet is that every time a user makes interface lacking in the changes, the spreadsheet automatically recalculates all the other related first generation of PCs: values. Apple II, CP/M, MS- Nowadays, spreadsheets also allow easy creation of charts and offer useful DOS. statistical and mathematical functions. The best known commercial spreadsheet application is Microsoft’s Excel , but After the release of MS there are also free, open-source applications with similar functionality and even Windows 2.0 in 1987, partial compatibility, notably OpenOffice.org ’s Calc , LibreOffice Calc (which Excel became its shares an ancestor with Calc), Gnumeric from the long-running GNU project flagship application, and and the online Google Sheets . came to dominate the In this course we use OOo Calc because it demonstrates the features of a market. good spreadsheet application, and is free. Since Excel is more widely used in industry, differences between the two applications will be noted periodically. Excel on Windows 2.1. http://en.wikipedia.org/wiki/Image:Excel2.png ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 7 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 8 Problem Solving Problem Solving with OOo Calc* • Calc allows you to easily solve many of the problems that arise • Preparing to Solve a Problem during the analysis phase. – What is the overall purpose of the problem (define)? • Calc provides features that allow you to: – What information is known ( input )? – Import, export, store, process and sort data – What information must be determined ( output )? – Display data graphically – Analyse data statistically – What fundamental principles apply to the problem? – Solve optimisation problems – What will be the overall solution strategy ? – Find relationships between data sets (fit algebraic equations – How can we check correctness our solution? through data sets) – How can we test our solution(s)? – Solve single and simultaneous algebraic equations – etc, etc * All those O’s (sometimes with an A for Apache, who now support it) can get a bit tedious. Unless there’s a risk of ambiguity let’s just call it Calc from now on. ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 9 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 10 Sheet Structure Basics of a Sheet name box shows selection formula bar shows active cell Name box (current range or active cell) contents (formula or constant) has address of active cell columns constant (numeric) range (click rows Active cell has bold and drag border, and row/col mouse, last labels are highlighted cell is active) Each sheet is constant formula divided into cell D10 (string) result rows and columns Every cell in a spreadsheet contains either a constant or a formula Rows are labelled as integers starting from 1 (up to 1 million+); A constant is an entry that the spreadsheet does not change, column labels are from A to Z, AA to AZ, BA to BZ, etc.. (up to 1000+) for example, test marks, student name or a date. The intersection of a row and column forms a cell . Each cell has a A formula is a combination of numeric constants, cell references, unique cell reference . For example, the cell at the intersection of arithmetic operators, and functions that returns the result of a calculation. column D and row 10 is called D10 Formulas are prefixed by an equals sign ( =). ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 11 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 12 ENGG1811 Spreadsheets 2 ENGG1811 Functions in Formulas Copy and Paste Commands A function performs a predefined computational task The copy command duplicates the contents of a cell, or range of cells For example the function AVERAGE(B2:B6) , in cell B8, calculates the The paste command copies the contents to the destination cell, or range average of all the cells in the range from B2 to B6 inclusive of cells. However, a formula is not copied exactly , but is adjusted as it is copied, depending on the destination cell. Range box and For example, if the formula in cell B8 is copied to cell C8 , it is adjusted so dependency arrows that the cells referenced in the new formula are in the same relative temporarily position as those in the original formula inserted by Tools - Detective Same principle applies to • inserting rows and columns • deleting rows and columns Calc provides many useful functions for mathematical, statistical, • filling operations financial and other tasks. Documentation can be found at original formula is https://wiki.openoffice.org/wiki/Documentation/How_Tos/Calc:_Functions_listed_by_category copied formula is =AVERAGE(B2:B6) =AVERAGE(C2:C6) ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 13 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 14 Filling Absolute vs Relative References In a formula, if the cell reference has $ signs in front of the row and column Filling combines copy and paste over a range of cells designation, it is considered an absolute reference and the cell reference Step 1: select range, usually in one direction, down or right remains unchanged throughout all copy/paste operations , e.g ., $B$10 Step 2: pick the Edit – Fill menu item to fill down (if vertical) or right (if A relative reference , on the other hand, adjusts during copy operations and is horizontal) specified without $ signs, e.g. , B2 (Calc also supports fill left and fill up) Auto-fill shortcut: original formula: =$B$10*B2+$C$10*C2+$D$10*D2 Step 1: select initial cell (the one with the original formula, B8) Step 2: grab the auto-fill handle (square dot at bottom right) copied formula: Step 3: cursor changes to +, drag the range, fill is completed on release =$B$10*B6+$C$10*C6+$D$10*D6 Extra-special deal: select two adjacent cells containing numbers, auto-fill A mixed reference uses a single $ sign to make the column or the row completes an arithmetic progression with tooltip feedback absolute, leaving the other as relative. For example F$6 or $F6 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 15 ENGG1811 © UNSW, CRICOS Provider No: 00098G Spreadsheets slide 16 Named Cells Formatting Cells The appearance of a cell can be changed by altering fonts, A special form of absolute reference is to give a cell a name , using letters only. borders, colour fill and number formatting, including indents Select a cell (or a range ) and enter the intended name in the name box , or pick Note that changing the format of a number affects the way the Insert – Names – Define from the menu (lists all existing names).