I previously talked the use of optimised trigonometric function through the use of the acml library. Trigonometric functions are coded in hardware through the x87 extension but it works on 80bits which is not necessary all the time. So software … Continue reading
New subject for this post. Since my new position at the crm2 in Nancy, I am working with optics. We set up an experiment on interferences and optical diffraction for demonstration. I am looking for a free open source software … Continue reading
Part of a study on the standard deviation of the electron density using Monte Carlo simulations, I was needing a fast way to calculate structure factors. I achieve this goal a while ago but I continued to improve things each … Continue reading
Vectorization is a nice concept in optimisation. It allows simulaneous calculations using special units in the processor. It is working only on special cases. I tried to apply to structure factors calculations. Fortran does not allow you to write vector … Continue reading
Small reveiw and feelings about a few graphical libraries: gnuplot, matplotlib, pgplot, plplot, dislin and R. Continue reading
This post is the continuation of the previous one on: CPU starvation I needed to rewrite a part of the code and it was a good opportunity to change the algorithm of the variance calculation. I was using the naive … Continue reading
A few weeks ago, I discovered that one of my programs has some cpu starvation issues. A cpu is starved when is waiting for the data. The most common cases are due high load on the disk but it can … Continue reading
I will be at the IUCR meeting in Madrid if anybody want to chat with me about computing/packaging/whatever, they are welcome 🙂 I’ll be presenting a poster on Linear transformations of variance/covariance matrices. abstract nº 1593 in MS62 Crystallographic Software: … Continue reading
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A while ago, I discussed a bit about code optimisation using valgrind: Spot bottlenecks. At the end I obtained something like 1sec for about 4000 reflections. Meaning about 250-500us/refl. In the meantime, I needed a much faster version. I am … Continue reading