Blog Archives

Playing with Primes in R (Part II)

June 17, 2010
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Playing with Primes in R (Part II)

Popping Part III off the stack—where I ended up unexpectedly discovering that the primes and primlist functions are broken in the schoolmath package on CRAN—let's see what prime numbers look like when computed correctly in R. To do this, I've had to roll my own prime number generating function.Personalizing primes in RFor what I want...

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Primes in R (Part III): Schoolmath is Broken!

June 13, 2010
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Here we are in Part III. Wait!? What happened to Parts I and II? Well, I started to write an article about Amdahl's law, parallelism and prime numbers, but found myself buried three levels deep trying to resolve problems with prime numbers in R. My normal inclination is to use Mathematica for such things, but I happened to...

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Primes in R (Part III): Schoolmath is Broken!

June 13, 2010
By

Here we are in Part III. Wait!? What happened to Parts I and II? Well, I started to write an article about Amdahl's law, parallelism and prime numbers, but found myself buried three levels deep trying to resolve problems with prime numbers in R. My normal inclination is to use Mathematica for such things, but I happened to...

Read more »

Go Guerrill-R on Your Data in August

June 8, 2010
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Go Guerrill-R on Your Data in August

Guerrill-R, get it? Register now for the Guerrilla Data Analysis Techniques (GDAT) class to be held during the week of August 9-13, 2010. The focus will be on using R and the PDQ-R for computer performance analysis and capacity planning.(Click on the...

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Simulating a Queue in R

May 30, 2010
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Simulating a Queue in R

In the GCaP class earlier this month, we talked about the meaning of the load average (in Unix and Linux) and simulating a grocery store checkout lane, but I didn't actually do it. So, I decided to take a shot at constructing a discrete-event simulatio...

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Load Testing Think Time Distributions

May 20, 2010
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Load Testing Think Time Distributions

One of my gripes about some commercial load testing tools is that they only provide a think time distribution (Z) that is equivalent to uniform variates in the client-script. If you want some other distribution, you have to code it and debug it yoursel...

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Emulating Internet Traffic in Load Tests

May 15, 2010
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Emulating Internet Traffic in Load Tests

One of the recurring questions in the GCaP class last week was: How can we make web-application load tests more representative of real Internet traffic? The sticking point is that conventional load-test simulators like LoadRunner, JMeter, and httperf, ...

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Significant Figures in R and Rounding

April 16, 2010
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Significant Figures in R and Rounding

This is a follow-on to my previous post about determining significant digits, or sigdigs, in performance and capacity planning calculations. Once we know how to do that, inevitably we will be faced with rounding the result of a calculation to the least...

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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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