Graphing Data Using a Logarithmic Plot

The majority of data can easily be plotted on a graph with equal intervals on the axes, for example 1, 2, 3 or 100, 200, 300 etc.. Some data, typically that which increases or decreases exponentially, cannot comfortably be graphed on such a scale without squashing the data up so much at one end that it becomes incomprehensible. The solution to this problem is to use a logarithmic scale.

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File Byte Reader

Writing code to read or write text files can be tricky because the exact contents of a file cannot be viewed in a text editor if the file contains non-printable characters such as line feeds or carriage returns. This simple utility program will take a filename as a command line argument and print out its exact contents, including descriptions of any non-printable or whitespace characters.

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Selection Sort

There are many sorting algorithms, often with variations and optimizations, and every now and again I will be coding some of them for this site.

A while ago I wrote a post on bubble sort and here is a follow up on another sorting algorithm called selection sort. As with bubble sort it’s not particularly efficient but it is simple to understand and implement.

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Using Valgrind to Detect Memory Management Problems

The C language has a reputation for being difficult to learn and to code in. I think this is unfair as it is actually a very small and simple language, but most of the perceived difficulty with using C comes from its memory management, or rather lack of. Only the smallest and simplest programs can get away with using auto variables: sooner or later you are going to have to use dynamic memory, opening yourself up to an extensive range of tricky bugs. There's no foolproof way to get round this, but you can catch most bugs before they wreak havoc in production with a brilliant little program called Valgrind.

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Allocating Dynamic Memory in Large Blocks

When creating a dynamic data structure it is tempting to allocate just the amount of extra memory you need to add each item. However, malloc, realloc or calloc are quite expensive in terms of resources so for situations where many items are likely to be added it is more efficient to allocate a large block of memory in one go. This can be gradually used up, and then another block allocated when necessary. In this post I will write a simple demonstration of this principle, complete with monitoring code to verify that we are in fact improving efficiency.

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Plotting Taylor Series Sine Waves

Previous posts have included an SVG library, memoization of factorials and Taylor Polynomials. In this post I will bring these all together to plot various sine waves created using Taylor Polynomials.

Very briefly, Taylor Polynomials are used to approximate functions, in this case sine and cosine, to any level of accuracy. We can plot these levels to show how they become increasingly accurate, which is the subject of this post.

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