# Month: September 2015

### Analytical convolution integral (Analytische Faltung) with Matlab and Maple

With $\sigma(t) = Heaviside(t)$ and $\delta(t) = Dirac(t)$
Function 1 (e.g. input signal/Eingangssignal):
$u(t) = \sigma(t-1) - \sigma(t-4)$

Function 2 (e.g. impulse response/Stoßantwort):
$g(t) = -\frac{1}{RC}\exp(-\frac{t}{RC})\sigma(t) + \delta(t)$

### Automatically convert videos in Powerpoint file (pptx) to a different format

I have been trying to convert a lot of embedded videos in pptx files to a different format lately due to compatibility issues on some systems, but have not found an easy and fast way – so I wrote this bash script.

The goal was to have a pptx with videos that can be played using Powerpoint 2010 or later on Windows as well as OS X without plugins. That seems to only be the case for MPG videos (mpeg1video codec).

To convert videos in a presentation

1. make sure that ffmpeg and a zip/unzip application is installed (ffmpeg can easily be replaced by avconv, but avconv somehow could not convert some files that were no problem for ffmpeg during my tests)