Write a simple algorithm in pseudocode

Pseudocode is an informal tool that you can use to plan out your algorithms. As you begin to write more complex code, it can be hard to keep an entire program in your head before coding it. A computer program generally tries to solve a well-defined problem using a well-defined algorithm. It represents the code and may look similar to the code or code constructs, but it isn't actual code.

Write a simple algorithm in pseudocode

Email Address A simple algorithm for correcting lens distortion One of the new features in the development branch of my open-source photo editor is a simple tool for correcting lens distortion. There are very few useful examples of lens correction on the Internet — most articles simply refer to existing software packages, rather than explaining how the software works.

Lens distortion is a complex beast, and a lot of approaches have been developed to deal with it. Some professional software packages address the problem by providing a comprehensive list of cameras and lenses — then the user just picks their equipment from the list, and the software applies a correction algorithm using a table of hard-coded values.

This approach requires way more resources than a small developer like myself could handle, so I chose a simpler solution: The effect is also fast enough to preview in real-time.

Before sharing the algorithm, let me demonstrate its output. Here is a sample photo that suffers from typical spherical distortion: This lovely demonstration photo comes from Wikipedia, courtesy of Ashley Pomeroy Pay special attention to the lines on the floor and the glass panels on the right.

Note the straight lines on both the floor and the glass panels on the right. My use of simple bilinear resampling blurs the output slightly; a more sophisticated resampling technique would produce clearer results. A key feature of the algorithm is that it works at any aspect ratio — rectangular images, like the one above, are handled just fine, as are perfectly square images.

Subscribe via RSS

Anyway, here is the required code, as pseudocode: I should mention that the algorithm works just fine without the zoom parameter. I added the zoom parameter after some experimentation; specifically, I find zoom useful in two ways: To give a specific example of the second circumstance, consider this fish-eye photo from Wikipedia, courtesy of Josef F.

Severe distortion like this is difficult to fully correct. If we attempt to correct the image without applying any zoom, the image must be stretched so far that much of the edges are lost completely: This is hardly the same photo.

The pier at the bottom has been completely erased! By utilizing a zoom parameter, it is possible to include more of the image in the finished result: Use of a zoom parameter allows us to preserve much more of the photo. When correcting severe distortion like this, you might want to apply a sharpening algorithm to the final image.

This sample image has no sharpening applied.

Motivation. We already know there are tools to measure how fast a program runs. There are programs called profilers which measure running time in milliseconds and can help us optimize our code by spotting bottlenecks. While this is a useful tool, it isn't really relevant to algorithm complexity. Prim’s algorithm is a greedy algorithm that finds a minimum spanning tree for a connected weighted undirected graph.. It finds a subset of the edges that forms a tree that includes every vertex, where the total weight of all the edges in the tree is minimized. Motivation. We already know there are tools to measure how fast a program runs. There are programs called profilers which measure running time in milliseconds and can help us optimize our code by spotting bottlenecks. While this is a useful tool, it isn't really relevant to algorithm complexity.

Again, I only use a simple resampling technique; a more sophisticated one would produce clearer results at the edges. The fun begins at line I also include an optional radius parameter, which allows the user to correct only a subset of the image rather than the entire thingbut other than that the code is identical to what you see above.Introduction.

G enetic algorithms are one of the best ways to solve a problem for which little is known. They are a very general algorithm and so will work well in any search space. All you need to know is what you need the solution to be able to do well, and a genetic algorithm will be able to .

How to Write Pseudocode: 15 Steps (with Pictures) - wikiHow Michael Skinner Introduction Genetic algorithms are one of the best ways to solve a problem for which little is known. They are a very general algorithm and so will work well in any search space.
Motivation Pseudocode implementation[ edit ] The algorithm can be expressed as 0-based array:

Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm that repeatedly steps through the list, compares adjacent pairs and swaps them if they are in the wrong order. The pass through the list is repeated until the list is sorted.

The algorithm, which is a comparison sort, is named for the way smaller or larger elements "bubble" to the top of the list.

write a simple algorithm in pseudocode

We've partnered with Dartmouth college professors Tom Cormen and Devin Balkcom to teach introductory computer science algorithms, including searching, sorting, recursion, and graph theory.

Learn with a combination of articles, visualizations, quizzes, and coding challenges. Understand why pseudocode is useful. Pseudocode is used to show how a computing algorithm should work.

Coders often use pseudocode as an intermediate step in programming in between the initial planning stage and the stage of writing actual executable code. One of the new features in the development branch of my open-source photo editor is a simple tool for correcting lens distortion.

I thought I’d share the algorithm I use, in case others find it useful. (There are very few useful examples of lens correction on the Internet – most articles simply refer to existing software packages, rather than explaining how the software works.).

Prim’s algorithm is a greedy algorithm that finds a minimum spanning tree for a connected weighted undirected graph.. It finds a subset of the edges that forms a tree that includes every vertex, where the total weight of all the edges in the tree is minimized.

Bubble sort - Wikipedia