Philipp Janert

Philipp Janert

Areas of Expertise:

  • data analysis
  • data modeling
  • mathematical modeling
  • consulting
  • speaking
  • training
  • writing

Philipp K. Janert provides consulting services for data analysis and mathematical modeling, drawing on his previous careers as physicist and software engineer.

He is the author of the best-selling Data Analysis with Open Source Tools (O'Reilly), as well as Gnuplot in Action: Understanding Data with Graphs (Manning Publications). He has written for the O'Reilly Network, IBM developerWorks, and IEEE Software. He holds a Ph.D. in theoretical physics from the University of Washington.

Visit his company website at www.principal-value.com.

Feedback Control for Computer Systems Feedback Control for Computer Systems
by Philipp Janert
October 2013
Print: $39.99
Ebook: $33.99

Data Analysis with Open Source Tools Data Analysis with Open Source Tools
by Philipp Janert
November 2010
Print: $39.99
Ebook: $33.99

Recent Posts | All O'Reilly Posts

Philipp blogs at:

The Essence of Feedback Control

March 12 2014

A while back, I wrote up some notes on the use of feedback control in auto-scaling server instances in a data center. Afterwards, a reader contacted me to ask whether the article didn’t “boil down to ‘pick your auto-scaling metrics … read more

Self-Adaptive Is Not The Same As Feedback

November 12 2013

In a series of posts (Part 1, Part 2, Part 3, Part 4, Part 5, and Part 6), we have introduced the idea of feedback control as a way to keep complex systems on track, even when subject to uncertainty … read more

Feedback Controller Tuning

November 05 2013

In the last post, we introduced the PID controller for use in feedback loops: or, in a discrete-time software implementation: sum += error output = kp * error + DT * ki * sum + kd * (error - prev) … read more

Feedback Controllers

October 29 2013

In the previous parts of this series (Part 1, Part 2, Part 3, and Part 4), we introduced feedback as a design principle or paradigm, that can help to keep systems “on track”, even in the presence of uncertainty and … read more

Feedback is Different

October 22 2013

In our last post, we pointed out that feedback is different from common algorithmic thinking. In the current post, we will discuss these differences in more detail. Typical algorithms tend to be deterministic, and are grounded in the assumption that … read more

Why Feedback?

October 16 2013

In two previous posts (Part 1 and Part 2) we introduced the idea of feedback control. The basic idea is that we can keep a system (any system!) on track, by constantly monitoring its actual behavior, so that we can … read more

The Feedback Principle

October 08 2013

In a previous post, we introduced the basic feedback concept. Now it is time to take a closer look at this idea. Feedback is a method to keep systems on track. In other words, feedback is a way to make … read more

Introducing Feedback

October 02 2013

Feedback is the very simple idea that you can control a complex system through the constant application of small corrections, which are applied to “nudge” the system towards its ideal operating point. This idea is at the same time obvious … read more

Recent Posts | All O'Reilly Posts

"I love this book a lot."
--Rik Farrow, ;login:

"This book is perfect for hands-on readers, wanting to achieve specific goals without getting entangled in formal definitions by getting right to the point. Here is an analogy: a Common Kite is depicted on the front cover of the book and as the bird waiting for its prey, you’ll be able to analyse the situation, understand it and take a clear decision after this read."
--Mathieu Hanna, Adviso

"This book offers a deep approach to real world tasks. There is much more text than code...It is hard to fault this book except perhaps that at nearly 500 pages, it is too short! "
--Neil McNaughton, Oil IT Journal

"Data analysis using open source tools is a straightforward, well explained and practical book which does not give just a laundry list of techniques but also useful pointers in how to use them intelligently. The book...is strongly recommended."
--Manoj Rengarajan, BookPleasures.com

"Data Ana­lysis with Open Source Tools by Phil­ipp K Jan­ert is a simply superb, solid and exhaust­ive syn­thesis of instruc­tion, work­shops and hands-on exer­cises designed for those ser­i­ous about con­duct­ing pro­fes­sional data ana­lysis. This is not a light­weight under­tak­ing...All in all, this is a very good book. It actu­ally does more than it prom­ises and deliv­ers a com­pre­hens­ive and effect­ive course in data ana­lysis with superb hands-on exer­cises to drive home the learning."
--Shawn Day, randomosity