Matrix inversion in Excel

Even the newest version of Excel has a limit on taking the inverse of a matrix. The maximum size is 52×52 (don’t ask me why this limit exists). What you get if you use minverse(your matrix) for a big matrix is this:

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Fortunately, there is a nice add-in programmed in C that does the trick. It was developed for Excel 2007 and earlier but it works fine in the newest version (2013).

You can download it from http://www.xcell.excelabo.net/english and it works like the inverse function in excel. Instead of minverse(….) you use minverse.ext(…).

PS. If you want to take the … Read the rest “Matrix inversion in Excel”

Getting rid of some annoyances when opening or saving in Excel 2013 (and Word, Access)

The new Office version (2013) has lots of new features, but also some annoyances. Especially saving and opening files need much more clicks.

If you want to open a file, Excel opens with a start screen. Disabling this one is easy: just go to File-Options-General Tab and disable “Show the Start Screen…”.

If you want to save a file, this is what appears in Excel

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Now you have to click on Browse to search the directory you want to save your files. It goes faster as follow, if you set the following options (see arrows) and set your favorite directory:… Read the rest “Getting rid of some annoyances when opening or saving in Excel 2013 (and Word, Access)”

Managing papers with Org-Mode and Reftex

Writing papers means reading lots of papers, and I often lose track of all the papers I am reading: Where did I file a certain paper? Which paper did I start reading? Which paper might be interesting?

A reading list would be nice, but such a list should be easy to handle. I have all my papers catalogued in JabRef and use AucTex and RefTex for writing and Org-Mode for my tasks.The solution should therefore combine the strength of all three. I found a nice post on how to this (http://tincman.wordpress.com/2011/01/04/research-paper-management-with-emacs-org-mode-and-reftex/) and adopted it to my needs.

Here … Read the rest “Managing papers with Org-Mode and Reftex”