Author name: Martin Andersson

[SOLVED] Black screen in TeamViewer on Mac Mini

  When pulling out the HDMI cable from a Mac Mini, the TeamViewer ses­sion on another com­puter gets a com­pletely black (or white screen). When insert­ing the HDMI cable again into the Mac Mini, the desk­top is shown prop­erly. This prob­lem was con­firmed by the  TeamViewer sup­port, which is very good by the way. They …

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[SOLVED] FileSystemWatcher problem

The FileSys­temWatcher .NET class lis­tens to the file sys­tem and it is catch­ing any changes and noti­fi­ca­tions in it. When direc­to­ries, or files in direc­to­ries, are changed, events are raised. When a file is cre­ated, the FileSys­temWatcher class will nor­mally be noti­fied twice. How­ever, up to 4 or more “events” can be fired depend­ing on …

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One bluetooth keyboard, one monitor, but TWO macs.

I use and HDMI TV as mon­i­tor, dif­fer­ent macs on dif­fer­ent HDMI chan­nels and it was really tricky for me to find out how to switch between them using ONE blue­tooth key­board and track­pad. The prob­lem is: You have to cut the estab­lished blue­tooth key­board and touch­pad con­nec­tion in order to be able to establish …

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[SOLVED] SugarSync on Mac puts files in Trash, “alias” problems

Like many oth­ers, I have started using cloud ser­vices to sync my data across com­put­ers. Although there are many nice alter­na­tives like Drop­box and so on, my choice until now is Sug­ar­Sync. It is very nice and it has com­pletely removed the man­ual copy­ing of files using FTP that I used to do. I really …

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The numerical estimate of matrix rank

The most com­monly used func­tion to cal­cu­late the matrix rank is prob­a­bly the one in the MATLAB soft­ware pack­age [1]. It is based on the cal­cu­la­tion of sin­gu­lar val­ues of the matrix A, and the num­ber of sin­gu­lar val­ues that are greater than some tol­er­ance defines the rank. The algo­rithm is sim­ple: r = svd(A); …

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A numerically stable PLS algorithm

Dur­ing 2011 year, I have tried many dif­fer­ent ways of mak­ing a PLS algo­rithm (PLS1) as sta­ble pos­si­ble. The goal was to make it as numer­i­cally good as the SVD imple­mented in MATLAB. The pseudocode that solved the PLS1 case for one y‑varable is shown below and it includes the addi­tion of null vec­tors to …

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Numerically good null spaces

There are many meth­ods to obtain null vec­tors to a given set of vec­tors. One of the numer­i­cally best meth­ods is imple­mented in MATLAB, based on sin­gu­lar value decom­po­si­tion, SVD. Null vec­tors can be used for many dif­fer­ent things; one of them is to remove prop­er­ties that are ore orthog­o­nal to another, given prop­erty. Such …

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A fast Householder bidiagonalization algorithm

Please note that this is not regard­ing the Lanc­zos or the PLS bidi­ag­o­nal­iza­tion algo­rithm. This is about the House­holder bidi­ag­o­nal­iza­tion algo­rithm. The dif­fer­ence is huge. For exam­ple, there are no y‑variables in the House­holder decom­po­si­tion. It is a decom­po­si­tion of X that results in a fac­tor­iza­tion with a bidi­ag­o­nal matrix in the mid­dle, sim­i­lar to …

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PLS regression — NEW animation

Dur­ing the con­fer­ence in Cape Town on Near Infrared Spec­troscopy, NIR2011, I had a keynote in the chemo­met­rics ses­sion. I pre­sented a com­par­i­son of three dif­fer­ent meth­ods for mak­ing cal­i­bra­tions includ­ing the LOCAL con­cept by Shenk and West­er­haus, and fol­lowng that, I pre­sented another com­par­i­son, on dif­fer­ent PLS algo­rithms. As a link between these two …

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