Python scripts

These are python scripts I've found useful in my own work. If you don't have python available on your machine, I'd recommend you consider getting it, as it's a useful tool and it's freely available for most platforms. Go to the Python  website for more information on python.  NOTE:  these scripts are old, having been written for the 1.5.2 version of python in the late 1990's.  Some of the functionality here has been obsoleted by things put into python's standard library or made part of the language (such as sets).

This is a python script that will generate most any linear isotropic graph paper by creating a PostScript file that draws the page. You can use ghostscript (see the script's comments) to convert the file to a PDF or an image bitmap.   Someday I'll also make it construct log axes too.

This python script will calculate various readability indexes for text files, such as the Gunning Fog Index, the Flesch-Kinkaid Grade Level, etc.  I use this tool to help ensure my writing is about at the 8th grade level, which is about the level of Reader's Digest.  

This script will produce a list of readable words from an HTML file, all in lower case, one per line.  You could then run the list of words through a spell checker.  I wrote this script in the hope that people on the web would spell check their web pages before publishing them.  :^)

iapws95.zip

This zipfile contains C++ and python code that implements the IAPWS95 equations for the thermodynamic properties of water.  You might also want to take a look at John Pye's freesteam project.  I wrote this code in November of 2004 in anticipation of getting some contract work doing a redesign of a steam turbine impeller, but the work never materialized.  Thus, the code hasn't been carefully validated in a real-world application.  If someone does use the code carefully, I'd appreciate any fixes and more unit test code to incorporate back into the package.  You might also search John's site, as he mentioned in an email in November 2005 that he thought there was an error in one of the second derivative equations (I lost his email, but I think it was one of the deltadelta ones, probably for phi)..

Default
    xref.cpp: [2] 566, 1514
Define
    xref.cpp: [1] 1505
Dictionary
    xref.cpp: [5] 254, 257, 364, 387, 401
DictionaryContainer
    xref.cpp: [5] 219, 224, 603, 1444, 1488
DictionaryContainerIterator
    xref.cpp: [3] 220, 226, 605
Do
    xref.cpp: [4] 479, 499, 556, 560

novas.py

This is a translation into python of some C code from the US Naval Observatory.  It contains routines that are nearly identical to those used for calculations of the Astronomical Almanac.  Combined with accurate ephemeris data, it should be capable of accurate astrometric calculations.  The python code generates the same results for the test vectors used by the C code.  Here are some notes I made on it.

hc.exe

This is an RPN calculator (run at a 32 bit Windows command prompt) loosely based on HP's calculators (especially my beloved HP-42S).. Type 'hc -h' to get a man page to stdout. Type ? and ?? in the program to get brief help.

The hc stands for hex calculator, which is what it was in the mid- 90's when I wrote it. But then I wanted it to have floating point calculations too, so I added a bunch of new stuff in a C++ rewrite in the late 90's. I've been using it everyday since. There are a couple of obscure commands that are broken, but most things seem to work fine.  Some day I want to rewrite it in python and add physical units, complex numbers, rational numbers, and interval arithmetic.  Take a look at frink in the meantime -- Alan wrote it in Java and it has wonderful support of units.

This tool is free, but I'm not planning on providing the source code.

Produces a list of files that are candidates for turning their execute bit permission off.  On Windows XP, when you use cygwin, external programs can create or modify files and leave their execute bit set.  Later, when you do an ls, you see a sea of green (or whatever color you have executables set to).  This script turns off the execute bit on all files that are not .exe's or some kind of script.  It can also act recursively.

ShopTrig.pdf

In the shop, the need to solve triangles pops up frequently.  To solve any triangle, you really only need a few pieces of knowledge:  the definitions of the sine, cosine, and tangent of a right triangle's angle, the cosine law, the sine law, and the fact that the angles of a triangle sum to 180 degrees.  This white paper gives these laws, then shows a few examples of their use.  It also gives Euler's Formula, a very useful thing to know.  In case you were wondering, the Pythagorean Theorem is a special case of the cosine law.

irr.py

If you deal with data files from a spectroradiometer, this script could be handy.  I use it mainly to calculate irradiance over a wavelength band from a spectral irradiance data file.  It is written to work with StellarNet spectroradiometer files, but it can easily be modified to work with other data files.  The weighting option -w weights the data with the weighting function given by the 2006 TLVs and BEIs by the American Conference of Government Industrial Hygienists.

Usage:  irr.py op parameters
Operates on StellarNet spectrum files.

int[egrate] [-w] lambda1 lambda2 file1 [file2...]
  Prints the integrated irradiance for a StellarNet irradiance file
  integrated over the indicated wavelengths.  If the -w option is
  given, the effective irradiance over the UV band is printed.

dif[ference] file1 file2 output_file
  Calculates the difference between two spectra and writes it to the
  output file.

OO_math.pdf

This is a short two-page document that introduces the equation-writing capabilities of Open Office 2.0.  While it's not industrial strength like TeX or LaTeX, it is quite capable and free.  If you occasionally need to stick equations in your documents, this could be a good tool.

I put this cheatsheet together to remind me of how to do things in Open Office's equation writer.  I print it out on  a single sheet of paper and keep it next to my computer.  Please note this list is not intended to be complete -- it contains a list of the things I am likely to use.

This is a C++ program that lets you design a voltage divider from the resistors you have on hand.  The zip file contains the divider.cpp file along with a Windows executable.  A PDF file also shows a simple and ingenious resistor storage system my wife came up with that lets me find a resistor in a matter of seconds.

gauge.cpp

A C++ program to print out combinations of inch gauge blocks that yield a desired composite length.  I have a second-hand set of gauge blocks I purchased inexpensively on ebay.  They are missing about 20 blocks.  It is difficult to figure out the blocks to use for general sizes, so I wrote a program to examine all of the combinations.  This problem is technically known as the subset sum problem and is known to be a difficult problem to solve -- there is no known algorithm that can solve the problem in time proportional to a polynomial of the problem size.  The brute force algorithm used here is exponential; however, it happens to solve the practical problems I'm interested in associated with the gauge block set I use.  It will also find one or all of the gauge block stacks for 36 and 81 block standard sets for a variety of desired dimensions.

While the purchase of a new gauge block set is probably beyond the financial means of most home shops, don't rule out the purchase of a used set.   I use my beat-up gauge block set quite a bit more than I thought I would.  For example, I'm designing a simple radius turning attachment for my lathe that will sit on top of the compound slide.  I needed the distance from the top of the slide to the spindle axis of the lathe.  It was easy to do with gauge blocks and I'm confident of the results:  I just chucked an edge finder in a collet chuck and used the gauge blocks to measure the height.  I could even account for the 0.0012" of runout of the edge finder and collet.