# Author Archives: mateusz

## Java wrapper for the Fortran L-BFGS-B algorithm

I have moved the source of my L-BFGS-B wrapper library from my university page to a more convenient hosting place: https://github.com/mkobos/lbfgsb_wrapper . The wrapper is a Java library proxy for the L-BFGS-B quasi-Newton optimization library. The original implementation is written … Continue reading

## Java PCA transformation library

I wrote a Java library implementing Principal Component Analysis data transformation. About two years ago I needed such an algorithm implemented in Java and I was not able to find one, hence this library. The library along with a more … Continue reading

## Creating data frame row-by-row in R

When manipulating data in R, I often find myself in a situation where I have to create a new data frame in an iterative row-by-row way. There are approaches to do it this way, but a natural question is which … Continue reading

## Concurrent tree crawler

I needed an application to crawl a web site containing archive issues of certain magazines and download selected articles. To access the site, you had to log in using a web form. The web site was constructed in a hierarchical … Continue reading

## Reader-Writer lock with priority for writers in Python

I needed a reader-writer lock to use in the second readers-writers problem with python threads. In this problem, many readers can simultaneously access a share, and a writer has an exclusive access to this share. Additionally, the following constraints should … Continue reading

## Comparison of application of Rcpp and rJava in R

Introduction I implemented a simple algorithm that computes distances between all pairs of given set of n-dimensional points. The algorithm is implemented in C++ and Java. To communicate with C++ code, I use R’s Rcpp package. To communicate with Java, … Continue reading

## First entry

Welcome to my blog. I plan to place here some programming-related things that were useful to me and hopefully will also be of use to a wider audience.