The Python programming language.
I’ve just released a self-contained Fortran module that solves a system of linear equations using the LU decomposition. Download the Fortran linear solver from github This module is based on code that was implemented and released on the Web by Jean-Pierre Moreau. His implementation was based on one of the Numerical Recipes books. I updated […]
A self-contained Fortran linear equation solver Read More »
I’ve recently gained a lot of experience with Sage, an open-source alternative to MATLAB, Mathematica, Maple, MuPAD, and Magma. Here are a couple of links to check out: Public notebook servers–try it online right now! Interactive examples with Sage Mathematical publications citing Sage
Sage: open-source mathematical software Read More »
Linear time-invariant (LTI) systems are widely used in the field of signal processing. Scipy contains powerful tools for simulating LTI systems in the scipy.signal package, but they are not well documented. I will provide a simple example that demonstrates how to use a few of the core classes and functions in scipy.signal for simulating LTI
Linear system simulation with Python Read More »
Scipy contains a good least-squares fitting routine, leastsq(), which implements a modified Levenberg-Marquardt algorithm. I just learned that it also has a constrained least-squared routine called fmin_slsqp(). I am using simple upper and lower bound constraints, but it’s also possible to specify more complex functional constraints. What I did not realize, at first, is that
Constrained least-squares fitting with Python Read More »
In a previous post, I described how Python’s Pickle module is fast and convenient for storing all sorts of data on disk. More recently, I showed how to profile the memory usage of Python code. In recent weeks, I’ve uncovered a serious limitation in the Pickle module when storing large amounts of data: Pickle requires
Storing large Numpy arrays on disk: Python Pickle vs. HDF5 Read More »
I have recently started using f2py to call Fortran from Python. I have found this useful for two reasons: speeding up Python scripts by calling compiled Fortran code, and using Python as a unit testing framework for Fortran modules. Unfortunately, the documentation for f2py is rather sparse, and may not be completely up to date.
f2py: binding Fortran and Python Read More »
In a previous post, I explained how to use the Python profiler. The profile is great for finding out which parts of the code run the slowest, or are called most often. However, the profiler doesn’t give any information about how much RAM is being consumed, or where it’s being consumed. If your program needs
Profiling memory usage of Python code Read More »
Lookup tables and spline fitting are widely used by scientific programmers. A particular function may not have an analytic solution–in other words, it can’t be expressed as an equation of elementary functions. This might happen if the function were empirically determined from experimental data, or if the equation can’t be algebraically solved for one variable.
Lookup tables and spline fitting in Python Read More »
There are lots of good open-source tools that you can use to make high-resolution, publication-quality 2D plots. Personally, I like to use Python, numpy, and matplotlib. Unfortunately, it is much harder to find a good tools to make 3D plots. Older versions of matplotlib had rudimentary 3D support, but this was removed in version 0.98.
3D Plotting Software for Python::Part 1::PyX Read More »
I have released a new version of my Python class that generates VTK data files in the .vtu format, which is compatible with Paraview and other VTK applications. If you have downloaded the old one, please get the latest version, which incorporates some bug fixes and has been more thoroughly tested.
Updated Python class for writing Paraview (VTK) (.vtu) files Read More »