12 March 2015

Wonders of Numbers: Adventures in Mathematics, Mind, and Meaning

Fe de Errata

Small Errata for Hardcover First Edition of Wonders of Numbers

page 205, boxed equation, Chapter 89, near bottom: "c" should be superscripted

page 358, Chapter 89, 2nd line in Further Exploring: "c" should be superscripted

page 216, Chapter 95, line 3, missing upside-down F symbol. Should read "F(24)" not "(24)", where the "F" is the upside-down symbol. Similarly line 2 should read "Let's define a new function F(n)."

page 262, figure drawing error. Line segment misplaced. Figure 114.1 should have a line connecting point B to the dot directly to the the left instead of the line from the point below B to the point directly to the left.

page 374, figure drawing error. Line segment misplaced. Figure 114.1 should have a line connecting point B to the dot directly to the the left instead of the line from the point below B to the point directly to the left.
page 94, Equation 10 towards the bottom of the page is missing an italics "i" before the "sin".
page 379, it says " 9 + 9 + 999 = 1000 " should be " 9/9 + 999 = 1000 " 



I used to have a webpage where I was posting about recreational mathematics.
As usual, it can be found at archive.org:


10 March 2015

OC4J: org.apache.xml.dtm.ref.DTMManagerDefault cannot be cast to org.apache.xml.dtm.DTMManager

When using JDK 1.6 the following CastException may be obtained:

 org.apache.xml.dtm.ref.DTMManagerDefault cannot be cast to org.apache.xml.dtm.DTMManager

This is because we are using different
 [06/03/2015 11:42:52,105] com.sample.AutenticaAction.execute(AutenticaAction.java:331) - Error = java.lang.ClassCastException: org.apache.xml.dtm.ref.DTMManagerDefault cannot be cast to org.apache.xml.dtm.DTMManager
        at org.apache.xml.dtm.DTMManager.newInstance(DTMManager.java:137)
        at org.apache.xpath.XPathContext.(XPathContext.java:102)
        at org.apache.xpath.jaxp.XPathExpressionImpl.eval(XPathExpressionImpl.java:115)
        at org.apache.xpath.jaxp.XPathExpressionImpl.eval(XPathExpressionImpl.java:99)
        at org.apache.xpath.jaxp.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:184)
        at com.sample.AutenticaAction.selectSingleNode(AutenticaAction.java:59)
        at com.sample.AutenticaAction.execute(AutenticaAction.java:130)
        at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
        at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)

This was replicated in OC4J becasue we are using different xalan.jar

01 January 2015

09 December 2014

Mastering Regular Expressions, 3rd Edition Understand Your Data and Be More Productive, Jeffrey E.F. Friedl

Mastering Regular Expressions, 3rd Edition
Understand Your Data and Be More Productive
By Jeffrey E.F. Friedl
Publisher: O'Reilly Media
Final Release Date: August 2006
Pages: 544

Comprehending RegExp:

This is a classic regexp book !!!
that every programmer must read.

Even, if you already manage regexp, and took a compiler course at college, still there are several tips that may help you a lot in this area, including bounding cases: Greediness and Laziness Always Favor a Match, Speed and Efficiency, Summary: NFA and DFA in Comparison, Among others good titles (details of lookahead, lookbehinds, Posix regexps, etc.).

Also, provides some common examples that each coder must face in several projects: recognition of IP address, emails, etc., although this is not a cookbook, always is useful to see coding examples after theory However this is likelihood not as important as was 10 years ago (because there is a lot of examples in the net and cookbooks).  A look to how to add benchmarking in different platforms -languages- and optimization for regexps. As usual, you can go directly to any chapter related to your favorite implementation/language.

Perhaps, after eight years, it could consider some current RE frameworks, including those that use NFA, such us, ICU Regular Expressions, Automaton, etc. (this way the spectrum of examples is better). Although this paradigm of  never-ending engines are commented in the book, always is good to have an update (well, at least after five years).

20 November 2014

If Hemingway Wrote JavaScript, Angus Croll

If Hemingway Wrote JavaScript
By Angus Croll
Publisher: No Starch Press
Final Release Date: October 2014
Pages: 192
This book has an Interesting proposal, art is an important part of this book, an hybrid release, thinking out-of-the-box.

It express that Javascript is more creative/dynamic than Java (for instance), which makes it a little more risky ? :-) . Nice to read these conjectures in a book, beyond the common book prototype avoiding the structured order we see in a programming book (training us to be into a factory as creator of code (developer).

It gives classical assignments of an introductory programming course; using Javascript, which is the de-facto language for novice coders.

A good sense of humor has the author and must have the reader (well... geek humor), it gives ludic analysis to simple snippet codes. Giving an implicit criticism to the authors' work.

One way to open your mind, and probably a must have coffee table book.

It maximize the way to do the same task with different approaches with a versatile language. Again: more than a laugh we can get here.

I humbling reckon that several authors I didn’t know…. from this point of view, it helped me (forced me) to learn more about universal literature. It is amusing to see Roberto Bolaño as a Javascript coder ;-) 

05 November 2014

Software Architecture Fundamentals, Part 1, Understanding the Basics, Video, Neal Ford, Mark Richards

Software Architecture Fundamentals Part 1
Understanding the Basics
By Neal Ford, Mark Richards


Extensive video from two known Architects (book Authors: Neal Ford, Mark Richards) coaching about their experience and providing best practices and analyzing study cases in how to become a Software Architect.

It goes straight to the point, why do you want to become an Architect: better income, finally better salaries makes some roles more interesting, and what it requires for it.

It has plenty of good sentences, Some of of them:
  • "Often Negotiation and politics skills are more important than Technical Skills".
  • " The world best architectures are not the perfect ones, but rather the feasible ones".
  • "Design Patterns often have different approach to Functional Thinking".

Also it's discussed: documentation is very important, as seen in different paradigms, and college courses, however, as Agile manifesto mentions: "Working software over comprehensive documentation", then "codebase is the core":
  • "our blue print is the source code"
  • "compilation is building"
  • "software design is expensive"

So, the idea is to reflex about how to build easily and in a cheap way, coding is a complex task and very easily to obtain a wrong artifact.

As seen, this video gives full a great feedback, where many times I had to stop a replay many passages.

In the other hand, there is a great emphasis about soft skills, politics, and how a project can be feasible regarding these features.

At the end, an excellent introduction to different aspects of Software Architecture, including its different specialization, but always keeping a big picture view.

Corollary: Very clever coaching.

11 October 2014

Head First Servlets & JSP

To keep track of my small contributions to book's errata:

Now it is my two cents for Head First Servlets and JSP.


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I review for the O'Reilly Reader Review Program Project Euler