Since the apparition of area detectors, the storage of the frames resulting of the experiment has always been troublesome. The apparition of bigger and faster detectors increased the problem where a lots of big images are produced. Several methods exist … Continue reading
Crystals is using packed storage to store symmetric matrices. Packed storage is using a linear array to store only the unique data (Netlib packed storage). There is a huge penalty on the calculation by doing so in some cases. In … Continue reading
As part of my new position in Oxford, I have a new computer: An 8-cores Intel Xeon CPU E5-2665 with 16GB of memory. Enough cores to try if my library is scaling well in multi-threaded environments. The result is really … Continue reading
The cryptic warning “not vectorized: not suitable for gather” is from a report of gfortran on auto-vectorization. For a long time, gfortran was reporting this failed optimization on a very simple mathematical operation. I managed to find the cause today … Continue reading
In the Crm² lab, in Nancy (France), we have prototype of an hybrid pixel detector from the company Imxpad. The data from the detector are raw ASCII files that I need to convert into files suitable for integration software. We … Continue reading
Moore’s law has driven computing power for years and will probably continue for sometime even though it ends is coming. However, if during the first 20 years the increasing power was directly related to the frequency, it’s no longer the … Continue reading
The Sleef library is an optimised library for the calculation of mathematical functions: the trigonometric functions(sin, cos, tan, sincos), inverse trigonometric functions(asin, acos, atan, atan2), exponential and logarithmic functions(exp, log, pow, exp2, exp10, expm1, log10, log1p), hyperbolic/inverse hyperbolic functions(sinh, cosh, … Continue reading
The compiler gfortran is able to automatically vectorize part of the code. The flag “–ftree-vectorize” enable the auto-vectorization and some diagnostics are written on the screen at compile time with the flag “-ftree-vectorizer-verbose=x” (x is a number from 1 to … Continue reading
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
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