Guess the angle

January 2nd, 2010

scan of old postcard guess where the photo was taken from

Can you guess where the postcard photo was taken from? I’ve been printing calendars. Back to work Monday, kicking off with the data handling module.

Debian Lenny

December 27th, 2009

Detail of Lenny desktop on Asus Pundit

Debian Lenny works ok on my desktop computer, an Asus Pundit AH1 box with dual core AMD processors and nvidia graphics and sound. The Lenny release is the current ‘stable’ and so has slightly old packages (Firefox 3.0xx and OpenOffice 2.4) but runs fast. I can always upgrade to Squeeze (the current ‘testing’) when I find a vital reason to.

A lot of things just worked once I did a ‘net install’ from the ‘small’ cd image (just the base system and a package manager) and chose the desktop and standard options. The rest was downloaded over the hard wired internet connection, so I have the up to date packages, rather than installing from a ‘large’ cd and then updating most of the system.

I managed to find work-rounds for all the issues that have arisen so far, mostly from the Debian forums. Below is a quick list of my findings

The scanner just worked with Xsane, and Rhythmbox automatically downloaded the codecs for a couple of mp4 and aac tracks I have on my music player.

Solstice at 17:48 on 2009-12-21

December 20th, 2009

Jupiter is following the Moon down to the horizon

Jupiter is following the Moon at present, and this sight prompted me to dig up some of my old astronomical Web pages and spreadsheets. Below are some highlights. The Web site is available on this server in the kepler directory.

Screenshot of the solstice spreadsheet with 2009 data showing

My Solstice spreadsheet based on Jean Meeus’ routines from his Astronomical Algorithms is predicting the instant of the winter solstice for 2009 within one minute of the USNO prediction. Not bad for a simple spreadsheet.

Screenshot of spreadsheet that calculates and displays the altitude of the sun and moon for a given position on earth and instant

You can see how short the day is on the 21st by looking at a screen grab from my illustrative spreadsheet above. Click on the thumbnail to get the full resolution grab. You can download the spreadsheet in XLS (MS Excel) format. The Sun and Moon altitude spreadsheet will work in OpenOffice 3.1 but you can’t save in ODS format, if you do the graphic stops being hotlinked to the calculations.

I’ll try to sort that out!

             sun       c twi    n twi     a twi     moon
date        r    s   b    e    b    e    b    e     r    s
20091216  0813 1554 0732 1635 0647 1720 0605 1801  0832 1535
20091217  0814 1554 0732 1635 0648 1720 0606 1802  0916 1637
20091218  0814 1554 0733 1636 0648 1720 0607 1802  0949 1746
20091219  0815 1555 0734 1636 0649 1721 0607 1802  1012 1856
20091220  0815 1555 0734 1636 0650 1721 0608 1803  1031 2007
20091221  0816 1556 0735 1637 0650 1722 0608 1803  1046 2117
20091222  0817 1556 0735 1637 0651 1722 0609 1804  1100 2226
20091223  0817 1557 0736 1638 0651 1723 0609 1804  1112 2336
20091224  0817 1557 0736 1639 0651 1723 0610 1805  1125 ----
20091225  0818 1558 0737 1639 0652 1724 0610 1806  1138 0047

You can calculate the sun rise and set times, the twilights and the times of moonrise using my javascript sunrise calculator. This javascript uses a slightly more robust algorithm than the trial and improvement system that Meeus uses, and so it will work closer to the Arctic Circle.

I still get a number of inquiries about my approximate astronomical positions web pages. They are hosted on bodmas, but there is a mirror that has slightly out of date pages on that has a higher Google rank!

More quick number questions

December 15th, 2009

Download a pdf file with 40 (more) quick fire number questions.

Focus on equivalent fractions, rounding, and some questions embedding the four functions including with whole numbers and one or two decimal number questions in familiar contexts. No answers as yet but I might write a set out.

Quick fire number questions

December 7th, 2009

John Cage

Download a one side pdf worksheet with 30 quick fire non calculator number questions and numerical answers.

Questions include the four functions with whole numbers and decimal numbers, a few fractions questions including adding related ‘family’ fractions, percentages and fraction conversion, some ratio and rounding and a few problem questions. Designed as a sort of ‘speed trial’.

Free Mind

November 30th, 2009

Free Mind is an open source mind mapping tool

FreeMind by Jörg Müller and a team of contributors is an open source mind mapping tool written in Java. It is available for Windows, Mac OS X and Linux.

The package makes Buzan style mind maps with some repositioning of nodes and a variety of symbols. You can ‘fold’ nodes with a mouse click and insert a new node at the currently selected node by pressing the Ins button on the keyboard. FreeMind 0.8.1 (the current Windows release) can add notes to nodes. The only format that seems to export notes with the nodes is the OpenOffice Writer export format, and this produces an .sxw file. The resulting file gives an error when importing into OpenOffice 3.1, however the map does load as an outline view with the notes in place.

Because FreeMind is written in Java, I’m hoping I can get a copy to run off a USB stick on IT room student computers at College. That way, we can have students producing mind maps.

Revision PowerPoint

November 29th, 2009

New range of fractions un Unicode

The symbol palette in Microsoft PowerPoint has always included the quarter fractions. Now you get the thirds and the eighths. Handy for quick revision PowerPoint presentations.

You can download a PowerPoint file with 20 slides with quick revision questions for level 1 Maths students. Covers money calculation questions, area and perimeter questions, unit conversion questions, questions about finding fractions and percentages of quantities, and some directed number work.

You can also download a PDF file with the same 20 slides. The PDF version seems to be a lot smaller (200kb).