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Seeking Math Help

So I have this equation that’s great for finding one term.  Problem is, I need to solve for another term that’s scattered all across the right side.  I’m hoping someone here has the mad algebra skills I managed to lose in the two decades since I last took a math class and can help me out.

Here’s the original equation:

Q = (3.07 × F × Y × (1 + 1.4 × ((D/V) × e(-2 × D/V)))) / D2

I want to be able to solve for D, not Q; in other words, have a single D on the left and everything else on the right of the equation.  F, Y, and V are all variable terms; the e is the classic irrational constant.  I tried for quite a while to do this and ran very firmly aground.  The best I managed was this minor simplification:

Q = (3.07 × F × Y × (1 + 1.4 × (D / (V × e(2 × D/V)))) / D2

…and even that assumes that I did things correctly.  Here’s the original equation in pretty shoulda-done-it-in-MathML-but-oh-well form:

I can shuffle the chairs around, as it were, but never really get anywhere close to having a single D on the left.  “But it’s so easy!“, you may well be shouting.  That’s why you’re working for Google and I’m not.

I remember having questions just like this on tests back in college: “Given this equation, solve for blah”.  It’s been too long, though, and in all honesty I was never that great at this sort of thing in the first place. Help, please?

[Update 14 Jan 09]: several commenters have shown that what I’m trying to do is impossible.  Frustrating, but that’s math for you.  Looks like I’ll have to take another approach.

Fixing Postcodes

In case anyone’s interested, I finally updated the ZIP archive of all the countries and postcodes from the 2008 ALA survey.  The two files are sorted like before, but this time leading-zero postcodes haven’t had their leading zeroes stripped by Excel.  Oh, Excel.

I have learned way more about Excel’s “helpful” handling of CSV and text imports than I ever wanted to know.  The basic drill is, if you want to open a CSV or text file but don’t want Excel to be “helpful”, don’t drop the file onto Excel or double-click the file icon.  No no!  That would be too easy.

Instead, launch Excel, select “File > Open”, and then select the CSV or text file you want to open in the file browser.  Go through the Text Import Wizard carefully:

  1. Tell Excel that the file is delimited on the first screen.  (Or, if it isn’t, then don’t.  I bet it is, though.)
  2. Tell Excel what delimiter you’re using on the second screen.
  3. Then—this is the crucial bit—on the third Wizard screen, select the columns you don’t want Excel to “help” you with and set them to “Text”.  Be careful about setting all the columns as “Text”, though: if you have non-ASCII characters, Excel will “helpfully” replace their contents with octothorpes when you try to export the data later.  Such “help”!  It’s so “helpful”!

Yay!  An open file where the data is all in its original state!

Now you can save the file as an Excel workbook and it should (but please note my use of the word should) leave your data alone.  Ditto if you do “Save As…” to export to CSV or text again, which you might do if you run some calculations and want to capture the result in a basic, portable format.  But remember!  If you ever want to open those CSV/text files in Excel, you can’t just open them.  You have to go through the whole text-import process again.

So the survey files now contain actual useful data, especially for countries where postcodes can start with zeroes.  (Which is a lot of them.)  The files also have the usual bits of abuse that come along with daring to ask people to supply optional information, because I didn’t even try to filter that stuff out.  So, you know, naughty words ahead.

In part, I’m posting this to leave a record for anyone else who runs into the same problems I had, and also to remind myself of what has to be done next year.  Also to provide a heads-up to anyone who’d like to grab the fixed-up data and do fun mapping stuff with it, as did some commenters on the previous post.

Survey Mapping

An anonymized copy of the data collected in the 2008 Survey has been turned over to some professional statisticians, as we did last year, and we’re waiting to hear back from them before moving into writing the full report.  But there’s no reason we can’t have a little fun while we wait, right?

So, calling all mapping ninjas: here’s a 136KB zip archive containing two tab-separated text files listing the countries and postcodes supplied by takers of the survey.  Before anyone has a privacy-related aneurysm, though, let me explain how they’re structured.

One of the two files is sorted alphabetically by country, with the postcodes as the second “column of data” (it’s country name, tab, postcode).  The second is the reverse: it’s sorted alphabetically by postcode, with the country names following each postcode.  This sorting should break any association they might have with the released data set, given that we won’t be including the postcodes in the released set.  (More on that in a moment.)

A word of warning: though I cleaned out some of the more obvious cases of people heaping abuse on us for even daring to ask the question, I can’t guarantee that the data set is perfectly clean.  There may be drops of bile here and there along with the usual collection of mistyped postcodes.  I know there’s at least one bit of obvious humor that I chose to leave in, so enjoy that when you find it.

We have two reasons to release this data this way at this point.  The first is to see what people do with it—heatmaps, perhaps, or one of those proportion-distortion maps, or a list of top-ten global postcodes or cities (or both).  Hey, go crazy!  I’d love to see a number of Google Maps/Yahoo! Maps/OpenMap/whatever mashups with this data.  That would be awesome.

The second reason is to ask for help with an API challenge.  Like I said, we’re not including the postcodes into the released data set.  What I would like to do instead is translate the postcodes into administrative regions (states, provinces, etc.) and put those in the data set.  That way, we can include things like “Ohio” and “British Columbia” and “Oaxaca”—thus providing a little bit better granularity in terms of geography, which was area of weakness in the 2007 survey.

Thanks to reading a couple of articles, I know how to do this for a single postcode.  But how does one do it for 26,457 postcode-and-country combinations without having to submit every single postcode as a separate request?  I’ve yet to see an explanation, and maybe there isn’t one, but I’d like to know either way.  And please, if someone does come up with a way, please show the work instead of just spitting out the result!  I’m hoping to learn a few things from the solution, but I obviously can’t do that without seeing the code.

One note: in cases where a postcode isn’t recognized or some kind of an error is returned, I’d like to have a little dash or “ERR” or something put in the result file.  That way we can get a handle on what percentage of the responses were resolvable.  Thanks.

Anyway, map and enjoy!

Survey Halfway

Okay, so yes, I posted about this two weeks ago and haven’t said anything since, but still: we’re halfway to the close of this year’s survey, so if you haven’t already done so, please devote ten minutes to taking it now!  You’ll make your voice heard along with literally thousands of fellow web professionals, hobbyists, and other people who make websites.  My copy of Excel is already weeping at the thought of having to crunch all that data, and I think that if there’s one thing on which we can all agree, it’s that anything which makes Excel cry is a good thing.

I TOOK IT! and so should you: The Survey for People Who Make Websites

Thank you.

I Took the 2008 ALA Survey

Ladies and gentlemen, it’s back, bigger and better than ever.  Please read Jeffrey’s wonderful introduction, and then start answering!  It shouldn’t take much more than 10 minutes to complete (it took me 6 minutes, 44 seconds, but who’s counting?).

I TOOK IT! and so should you: The Survey for People Who Make Websites

Last year, we had an astonishing 32,831 responses; I can only imagine where we’ll end up this year.  And just as with last year, we will report our findings and release an anonymized raw data set.

The more people who take the survey, the better the results will be, so please—post the link on any relevant sites, mailing lists, discussion boards, or other communities.  Print up flyers and post them around your town.  Anything we can do to get the word out!

Thank you.

The Really Perfect Ringtone

When I saw a couple of people link to “the perfect iPhone ringtone” last week, I had that sinking feeling that comes from being beaten to the punch.  I knew I should have stayed up an extra hour that one night and just gotten it done!

But wait, hold it, never mind, cancel the panic parade: it was not, in fact, the perfect ringtone.  Crisis averted!  Still, the sinking feeling lingered, reminding me of what could have been, so last night I sat down and got it done.  Now I bring to you the absolutely most perfect ringtone ever.

Feel free to preview it using that link, if you really feel that’s necessary, but frankly you should just charge ahead and download the .m4r AAC for instant ringtoniness.  If for some reason you’d rather have the audio source and do your own ringtone conversions, you can get the same file as a .m4a AAC or a comfy old .mp3.  And for all you completists, there’s a .zip archive of all three formats.

Go.  Ring.  Enjoy.

Expressive Sculptor

For those of you using Microsoft Expression Web, a free pre-release trial version of CSS Sculptor for Expression Web was announced by the WebAssist folks on Wednesday at MIX08.  So now you don’t have to put up with those snooty Dreamweaver users throwing you the mëtäl hörns every chance they get—throw ‘em right back!  Røck!

If you’re curious about CSS Sculptor, I posted in some detail about it when it was first released in August 2007, and there’s of course plenty of enthusiastic copy about it on the WebAssist site.

One thing that’s different about the Expression version as compared to the Dreamweaver version is that it doesn’t have an “Apply” button to apply the input CSS ito the preview window.  Instead, changes are instantly reflected in the little preview.  It’ll be interesting to see how users react to that, since it could mean that the previewed design shatters as the CSS is updated, and then snaps back together upon further changes.  Is that good or bad tool usability?  Hard to say; it could scare people into undoing the shatter-change and never pushing forward, but it could also help users more quickly gain a deeper understanding of CSS by seeing how things come apart and then go back together.  I guess we’ll find out!

Out of Order

Apologies to anyone who tried visiting meyerweb in the very near past and found it broken.  I’d noticed that suddenly all kinds of comment spam were getting past Akismet and landing in the moderation queue, and was just preparing to ask the spam-fighters about it when I discovered that the blog portions of the site were throwing a PHP error about not being able to find a function I’d written into a plugin.

At which point I discovered that all my WordPress plugins had been deactivated.  I know I didn’t do that, so how they all got turned off remains a bit of a mystery to me.  I’ve turned all the ones I need back on, and things appear to be back to normal.

So Akismet wasn’t being evaded by the spam: it was simply switched off.  Good thing my non-plugin defenses caught everything that poured in during the outage.  Which, come to think of it, must all have been direct-submit spam, since there wouldn’t have been a comment form available on the entire site.  So what they were really avoiding was my direct-submission defensive plugin, not Akismet.

Well, either way, other defensive measures protected the site, so all’s well there.  I’m certainly not thrilled about the site having been largely offlined for a short period, and again, my apologies to anyone who got blocked from information they wanted.

This episode has actually given me cause to reconsider my usual preference to put site navigation at the end of the document source.  When the PHP failed, the navigation was never served up.  Had I put it at the top of the page, it would’ve been present even though the blog posts were failing.  Getting to the static areas of the site would have been possible.  Due to my structural choices, a script failure dramatically affected the usability of the site as a whole.

Something worth thinking about as I slowly work on improving the organization of meyerweb.

July 2014
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