Counting sort in an \(O\left(n+m\right)\) sorting algorithm (instead of the usual \(O\left(n\log n\right)\)) for integer values, where \(n\) is the number of elements to sort and \(m\) is the width of the data type (e.g., \(2^{8}\) for byte). Its premise is quite simple. Given enough memory, it creates an array the width of the data […]
Whether threading an application or using distributed means, computing basics statistics becomes a bit more challenging. In the post (which I’ll update), I’ll break-down basic statistical functions for implementation in a distributed environment. Contents: Count Maximum Minimum Sum Average Variance Covariance Pearson Correlation Coefficient
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While appearing “old-fashioned,” command line programs still exist and are quite useful. In this post, I will share my little command line reader, which provides a few simple readers. It accepts prompt text and handles plaintext and password entry. While the former is quite simple, the latter requires a little background to avoid common mistakes.
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A message digest is simply a one-way cryptographic hash of a message. In theory, the results cannot be reversed; i.e., retrieving the message from the hash (hence, this is not a form of encryption, but a check). Message digests are commonly used to, e.g., sign messages, validate downloads, and protect passwords (in legacy instances –
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Enumerators are a commonly used data type to map a value to a predefined set of constants. As the data are entered, an integer iterator enumerates the values beginning with 0 in a plus 1 fashion. You can perform if-then-else style operations on enums using switch statements. Furthermore, it is possible to assign additional values
Two of the most basic profiling tactics are timers and memory analyzers. I have created a cheesy little set of classes that have come in handy more than a few times in these areas. The timer provides basics such as starting, stopping, and splitting time in milliseconds. It also allows for variable length precision, unit
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This post continues the conversation on Java Threads (Thread in Java and Threads in Java – Termination being the previous two), to introduce the concept of timed execution. This refers to the process of running threads until a predetermined amount of time has elapsed. Using heuristics as an example, some authors choose to compared based
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Threads were briefly introduced in the post Threads in Java. Here, we continue the conversation by introducing a way to terminate threads once one in a set reaches a prescribed condition. Thread termination example The example below is a simple guessing game. A value between 1 and 1 billion is chosen (500 million in this
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A Java Thread allows for segmentation and parallelization of a task. If using a single machine, threading is a natural option to boost performance. For instance, a quad-core, hyper-threaded computer can support up to 8 threads (though I’d recommend leaving 1 for the system, so 7 max). Each cluster node in contains 32 threads, so
Generating permutations can be quite tedious, especially when the number is large. The traditional way is to instantiate all at once, then retrieve each when needed. This, however, requires vast quantities of memory for very large sets, thus making them impractical in most research settings. For example, let the character set be the English alphabet
