Category Archives: Uncategorized

Fuzzy & Pixelated PDF Copy & Paste from macOS Preview

Too long, don’t want to read. Symptom. Cutting and pasting sections of PDF files from macOS / OSX Preview results in fuzzy and pixelated images where you were expecting vector PDF data to be copied and pasted. Correlated symptom. You will be … Continue reading

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PageRank beyond the Web

I just completed a survey article about uses of PageRank outside of web-ranking. The paper has been submitted to a journal, and I also posted the manuscript to arXiv. David F. Gleich. PageRank beyond the Web. arXiv. cs.SI:1407.5107, 2014. The … Continue reading

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Get Matlab to email you when it’s done running!

This is a guest post by Kyle Kloster, one of the students I’m working with at Purdue University. Kyle has been doing some large, long running experiments on big graphs. He writes: The random-walk transition matrices for Twitter, LiveJournal, and … Continue reading

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The data computer I want

This post is pure speculation, but they are notes of something I’ve been thinking about for a while. Here’s the computer I want to get for “medium data” matrix computations ~50TB. Quad 8-core Intel E5-48XX processors + motherboard ($10k) 1TB … Continue reading

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SVD on the Netflix matrix (Part 2)

About a week ago, we saw some basic performance stats on computing the SVD of the netflix matrix using Matlab‘s internal routines and the Propack software. One of the comments suggested trying ipython, scipy, and numpy. So we did! netflix_svd.py … Continue reading

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SVD on the Netflix matrix

Here, we consider three implementations of computing the SVD of the netflix matrix. Just to recap, the matrix has 17770 rows, 480189 columns, and 100480507 non-zeros. We are also considering the sparse SVD that treats the missing entries as 0, not the … Continue reading

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A call to update the Lake Arrowhead graph!

Please read Cleve Moler’s blog post about the Lake Arrowhead matrix too and look at the comments. That’s what got this all started! We’d like to produce a new version of this matrix with information from 2013. Once I have that, I’ll run … Continue reading

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Numerical Linear Algebra in Machine Learning

Notes from the Numerical Linear Algebra in Machine Learning Workshop Here’s a quick summary of some highlights from my notes about the NLA in ML workshop at ICML. First, it was fantastic in terms of speakers and audience. There were lots of great questions that … Continue reading

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How to use Matlab in a command line script or Makefile

This post is really for me as I managed to forget, misplace, or lose my notes on the last time I did this activity. If you wish to run a matlab m-file from the command line or from a Makefile, … Continue reading

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A person made of money is worth $1,000,000

After watching the Geico about a man made of money, I asked my wife. “If a person were actually made of $100 bills, how much would that be?” Neither of us knew the answer. So I set to find out! First, … Continue reading

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