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Thread ID: 58377	2005-05-30 02:03:00	MS Excel X-axis ontop?	jamesyboi (6579)	Press F1

Post ID	Timestamp	Content	User
359687	2005-05-30 07:41:00	i tried that because a guy on mr excel forums told me to do it. it doesn't flip the line graph or the digits, just the little lines / placeholders for the values Then do what I suggested above and also tick the box "Values in reverse order". I think this is what you want, although you're still not that clear. (Regarding other posts on this, I tend to take something like Voltaire's reputed view that "I disagree with everything you say, but will defend to the death your right to say it." I guess you can try doing graphs however you want them, even if only you know what they mean.)	rugila (214)
359688	2005-05-30 12:01:00	... correct - you use negative values.Mike. It may help if you consider a few further comments. Yes, it is correct to use negative values. It's also correct to use positive values, or even a mixture. It depends where you set your datum, and which way (up or down) you call positive or negative. Nautical charts for example usually specify a datum from which some heights are given as positive, and most depths are also given as positive. The datum on my chart of the approaches to Auckland is defined as "5.27m below a BM set in a concrete block on the eastern side of the bay on the southern coast of Whanganui Island". (Actually there are 3 such bays and the chart doesn't specify which. Woolshed Bay, the easternmost of the 3, is the most pleasant if you want to go look for yourself.) Anyway heights on the chart (typically on land) are given in metres (above mean high water springs) without pos or neg sign attached, and depths are also given in metres (reduced to approx lowest astronomical tide) likewise without pos or neg sign attached. e.g Rangitoto is 258 metres, a deep spot just west of Waiheke Island is 33 metres. For your assignment you can take datum where you like, and further, you can nominate distances up or down from it as either positive or negative as you like. If you want to communicate to others your measurements it's a good idea to specify carefully what you are doing just as the nautical charts do. For example, if like Luca Pacioli and the accountants of old, who invented double entry accounting primarily as a means of avoiding the negative numbers they didn't really understand, you likewise want to avoid negative numbers then you could take as your datum the deepest point you measure in your river (or a specified distance below this) and measure the river's depths as (positive)heights above this datum. Or if you have a special enthusiasm for negative numbers, as other posters on this forum seem to, then by all means take your datum as the river's surface or above. And any direction away from this datum (or origin) you could take as positive or negative as you wish, although if you also want to communicate your results to others it probably pays to find out the local conventions (i.e. the preferences of your assessor) and stick to these. However, there's nothing "correct" or "incorrect" about any of this stuff (unless you want to take issue with the interpretation of Pacioli's motivations). Perhaps this material, along with the previous suggestions about using Excel charts, might be of help with your geo assignment (or indeed with other topics.)	rugila (214)
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