Author Archives: Samuli Siltanen

About Samuli Siltanen

I am an applied mathematician interested in medical imaging. For example, I study probing the human body using X-rays or harmless electrical currents, and using computers and mathematical methods to form three-dimensional reconstructions of patients from the data so collected. In my free time I like to train with kettlebells and to photograph landscapes and animals.

Tomography of lotus root

I created this video out of a measurement session in my lab at University of Helsinki. Enjoy!  

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How to make black&white images look good

Grayscale pictures are very relevant, even in these highly digital days. One reason is that in print media it is much cheaper to publish images in monochrome rather than in colour. Another reason is the human visual system where, roughly … Continue reading

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Basic Principles of Mathematical Programming

Creating new mathematical algorithms can be fun and very rewarding. When all goes well, that is. Anyone who has taken a shot at mathematical programming knows how frustrating it is to debug programs crashing with obscure error messages or producing … Continue reading

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Including movies in LaTeX beamer

All technological gimmicks are allowed in today’s fierce scientific presentation arms race. Even videos! This is of course almost unheard of in the world of mathematicians who like to stick with blackboards and view OHP’s as useless snobbery. But the … Continue reading

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Precise positioning in LaTeX beamer

It is easy to become frustrated with the automatic layout of LaTeX when preparing talks using the beamer package. Namely, LaTeX places images in an often unpredictable way, and sometimes it would be important to keep two images on consecutive … Continue reading

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Explaining sine and cosine visually

Articles and presentations often benefit from geometric illustrations. But how to draw them? There are of course many software options for creating vector graphics, but it is practical to use as few different tools as possible. That’s why I rely … Continue reading

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Plotting a function of one variable

Let’s study one of the most common tasks in the visualization of applied mathematics: plotting a function on a real variable. Matlab’s default settings often need some tuning for a specific purpose. The example is very simple: plot the sine … Continue reading

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Displaying Image Data for Comparison

I am often faced with the problem of showing an “original image” and a “reconstructed image,” which may have completely different dynamic ranges. Namely, when working with ill-posed inverse problems, unsuccessful reconstructions sometimes amplify measurement noise a lot. However, it … Continue reading

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