Java Bytecode Assembly, Interesting concepts in the art of Computer Science/Software Development, maybe from time to time other pesky corp. related development issues.

Wednesday, January 20, 2010

Resetting cached password of Subclipse

I was asked to document a FAQ about Subclipse and cached passwords (my turn to play with the IT hat!). Here is the email (kept here for future reference).



Hello Friends,

Eclipse subversion plugin (Subclipse) will cache the username & password of the last user that did a successful commit with your eclipse installation.
This can be problematic if this user is not you, it turns out that until further notice all your svn commits will be under different username.

To resolve this issue, delete the following 2 folders:
rm -rf /opt/eclipse3.3/configuration/org.eclipse.core.runtime/.keyring
rm -rf ~/.subversion/
Then restart eclipse.

An alternative solution would be to kindly ask the busy IT department to change the svn password of the user under which your commits are being executed, then on first commit attempt Eclipse should prompt your for username & password, which will allow you to input your information.

Reference: http://nlp.cs.byu.edu/~rah67/wordpress/?p=4

Maxim.

Sunday, January 17, 2010

Running Average calculation implementation in Java

Quick blog and store note:

Here is a code to calculate average series of length N without the problem of overflow that naive average calculation could face.




/**
* Copyright (c) 2010, Maxim Veksler 
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, 
* are permitted provided that the following conditions are met: 
* 
* Redistributions of source code must retain the above copyright notice, this list
* of conditions and the following disclaimer.
* 
* Redistributions in binary form must reproduce the above copyright notice, 
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution. Neither the name
* of the http://bytecoded.blogspot.com/ nor the names of its contributors
* may be used to endorse or promote products derived from this software 
* without specific prior written permission.
* 
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/

/**
* Calculate average of arbitrary length series of doubles, running average ensures 
* result won't overflow.
* 
* Algorithm: CELLCOUNT represents number of cells calculated so far. 
* For each : cell
*  avg =  ((CELLCOUNT-1) * avg) + ((1/CELLCOUNT) * avg)
* 
* @param series vararg list of parameters (array of doubles).
* @return Average calculated from supplied series.
*/
public static double movingAverage(double... series) {
if(series.length < 1) {
   return 0;
  } 

  double avg = series[0];
  for(int i = 1; i < series.length; i++) {
   avg = (avg * ((double)i/(i+1))) + (series[i] * ((double)1/(i+1)));
  }
  
  return avg;
 }

About Me

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Tel Aviv, Israel
I work in one of Israel's Hi-Tech company's. I do 5 nines system development with some system administration. This blog will focus on the technical side of things, with some philosophical strings attached.