Month: July 2014

Revenge of the Animated GIF

Yes, now animated GIFs can be created using only Fortran code.  I present FGIF, now on GitHub.  It is a modified and updated version of the public domain code found on the Fortran Wiki.  It was used to create the image shown here (which

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SPICE N65 Released

JPL just released a new version of the SPICE Toolkit (N65).  According to the What’s New page, changes include: support for some new environments and termination of some old environments new Geometry Finder (GF) interfaces — illumination angle search, phase angle search, user-defined

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json-fortran 1.0.0

I just tagged the 1.0.0 release of json-fortran.  You’re welcome, interwebs.

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Rodrigues’ Rotation Formula

Rodrigues’ rotation formula  can be used to rotate a vector a specified angle about a specified rotation axis :   A Fortran routine to accomplish this (taken from the vector module in the Fortran Astrodynamics Toolkit) is: This operation can also

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GCC 4.9.1

GCC 4.9.1 has been released.  The big news for Fortran users is that OpenMP 4.0 is now supported in gfortran.

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Fortran Astrodynamics Toolkit

I’m starting a new project on GitHub: the Fortran Astrodynamics Toolkit. Hardly anyone is developing open source orbital mechanics software for modern Fortran, so the time has come. Most of the code from this blog will eventually find its way

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Here is a simple Fortran subroutine to return only the unique values in a vector (inspired by Matlab’s unique function). Note, this implementation is for integer arrays, but could easily be modified for any type. This code is not particularly

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C++ vs Fortran

I agree with everything said in this article: My Corner of the World: C++ vs Fortran.  I especially like the bit contrasting someone trying to learn C++ for the first time in order to do some basic linear algebra (like a matrix

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Modern Fortran References

In the last few years, a number of excellent books have been published about modern Fortran: R. J. Hanson, Numerical Computing With Modern Fortran, SIAM-Society for Industrial and Applied Mathematics, 2013. A. Markus, Modern Fortran in Practice, Cambridge University Press, 2012. M. Metcalf, J.

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Sorting with Magic Numbers

Updated July 7, 2014 Poorly commented sourcecode is one of my biggest pet peeves. Not only should the comments explain what the routine does, but where the algorithm came from and what its limitations are.  Consider ISORT, a non-recursive quicksort routine from SLATEC,

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