Blog Archives

Significant Figures in R and Info Zeros

April 11, 2010
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Significant Figures in R and Info Zeros

The other day, I stumbled upon the signif function in R, so I thought I'd take a look at what it does and compare it with some results discussed in Chap. 3 "Damaging Digits in Capacity Calculations" of my GCaP book, viz., Example 3.5 on page 31. The m...

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PDQ 5.0 Test Suite or … How I Spent My Weekend

June 29, 2009
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PDQ 5.0 Test Suite or … How I Spent My Weekend

I was planning to blog about the amazing time I had at Velocity 2009 last week, when this landed in my mailbox (edited for space and privacy): Subject: Seeking help with PDQ-R ...Date: Thu, 25 Jun 2009 15:51:21 -0500My name is James and I've be...

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August Guerrilla Class: Using R for Performance Analysis

June 29, 2009
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August Guerrilla Class: Using R for Performance Analysis

Registrations are still open for the Guerrilla Data Analysis Techniques (GDAT) class being held August 10-14, 2009. The focus will be on using R and the new release of PDQ-R for performance analysis and capacity planning.All Guerrilla classes are hel...

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Negative Scalability Coefficients in Excel

May 12, 2009
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Negative Scalability Coefficients in Excel

Recently, several performance engineers, who have been applying my universal scalability law (USL) to their throughput measurements, reported a problem whereby their Excel spreadsheet calculations produced a negative value for the coherency parameter (...

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Barry3-Apdex Also Lives in R

April 17, 2009
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Barry3-Apdex Also Lives in R

As a by-product of my presentation on the Apdex Index at the NorCal CMG meeting, back in February, Guerrilla graduate, Stephen O'Connell, went off and did an implementation in R. You can read about it in this month's CMG MeasureIT and download his R-s...

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PDQ 5.0 is on the Launch Pad

April 4, 2009
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PDQ 5.0 is on the Launch Pad

PDQ (Pretty Damn Quick) major release 5.0 is on the launch pad at Cape SourceForge. Because of a potential collision with the North Korean ICBM/satellite launch, we won't be filling the main liquid-hydrogen tank until next week (we don't want PDQ blame...

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Modern Microprocessor MIPS

April 2, 2009
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Modern Microprocessor MIPS

The question of how modern microprocessors compare with mainframe processors of yore, arises from time to time. The vernacular rate metric that has persisted for a long time (long in the history of computers, that is) is MIPS. Whether you approve of M...

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Streaming Hadoop Data Into R Scripts

March 23, 2009
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Streaming Hadoop Data Into R Scripts

Along the lines of Mongo Measurement Requires Mongo Management, the HadoopStreaming package on CRAN provides utilities for applying R scripts to Hadoop streaming. Hadoop is used on Amazon's EC2.

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i-Screen, u-Screen, Vee All Screen for Which Screen?

March 9, 2009
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i-Screen, u-Screen, Vee All Screen for Which Screen?

When I first came to the USA, it quickly became apparent that there was no such thing as, ice cream. You had to specify what flavor, what combination of flavors, what kind of cone, what you wanted on top of it, and so on. This is all enshrined in the s...

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Plotting PDQ Output with R

February 27, 2009
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Plotting PDQ Output with R

One the nice things about PDQ-R (coming in release 5.0) is the ability to plot PDQ output directly in R. Here's a PDQ-R script, together with the corresponding graphical output, that I knocked up to show the effect on the throughput curve of adding mor...

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