Archive | Computing

# $$math$$ versus $math$ in LaTeX

Let’s say you want to display some maths in LaTeX. You don’t want to use equation and related environments.

Inline maths is enclosed between dollar signs, and is formatted as part of the sentence.

A displayed equation is enclosed between pairs of dollars or between $and$. But $$…$$ and $…$ are not the same. For one thing, $…$ responds to the documentclass option fleqn to align the equations to the left rather than center them. Thus, we get this:

Where ‘Inline’ is indented because it starts a paragraph. First two displayed equations use $$…$$ and are centred, the last uses $…$ and is indented by a length called mathindent.

Here is the LaTeX code

\documentclass[fleqn]{article}
\begin{document}
Inline maths: a simple equation might be $x+y=1$.
The solutions to the quadratic equation
$$ax^2 + bx + c = 0$$
are given by
$$x=\frac{-b \pm \sqrt{b^2-4ac}}{2a},$$
which is to say
$x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}.$
\end{document}


Notice the argument ‘fleqn’ has been given to the article class, but $$…$$ did not obey it. $…$ did, but not all the way to the left. If you want the left aligned maths to be hard left, you need to redefine mathindent to be zero length:

\setlength{\mathindent}{0pt}


and this gives

Anyway.

# Comparing PDFs; diff-pdf, pdftotext, diff…

Command line tool diff-pdf at https://vslavik.github.io/diff-pdf/ is a very handy tool. It basically superimposes two PDFs to make the differences show up. It’s not a textual comparison as such. Here is the command line:

$diff-pdf --view test.pdf test_mod.pdf  The black bits are common to both files, the red is in one version and the cyan in another. If the differences result in new lines being inserted, the whole page turns blue/red, since the lines don’t match up any longer: So it is a very good way of isolating minor changes (say, between consecutive proofs of the same document) and checking if two files are actually identical (though conventional diff can indicate whether two binary files differ or not). It’s less good for comparing and decided which version is ‘better’ since the result can look a bit messy. Using conventional diff: $ diff test.pdf test_mod.pdf
Binary files test.pdf and test_mod.pdf differ


Use of pdftotext on both PDFs, then using conventional diff is pretty useful, too. Here is the output from just such a test:

$pdftotext.exe test.pdf$ pdftotext.exe test_mod.pdf
$diff test.txt test_mod.txt 1,3c1,5 < This is a very basic look at using METAFONT and gnuplot to make figures < for use in LATEX. I am using Linux, but the same process ought to work for < other LATEX environments; indeed, that ought to be one of its strengths. --- > This is an extremely basic look at using METAFONT and gnuplot to make > figures for use in LATEX. I am using Cygwin, but the same process ought to work > for other LATEX environments; indeed, that ought to be one of its strengths. > Here is some text added to make the line wrap and offset compared to the other > document. 36c38 < see. --- > see. Also, this document is really just to show use of diff-pdf. 42d43 < 5. If you like at this point you can try: 45c46,47 <$ gftodvi test2.600gf --- >
5. If you like at this point you can try:
> $gftodvi test2.600gf 78a81,84 1 > 2 > > Figure 1: Here is my pointless plot. 83,85d88 < 2 < < Figure 1: Here is my pointless plot.  No conclusion. Just noting that these tools are handy. Ende. # Plotly on cygwin; the absolute basics This has to be about the absolute basics. I don’t know anything else. Plotly (https://plot.ly/) is an interactive, online graphing tool. It can be called from JavaScript, Python, whatever. This post is about getting it to work through Python on Cygwin. This all mostly follows instructions on the Plotly website. (1) Installed via pip. What’s pip? A Python package manager. I ran the Cygwin setup.exe program and made sure that Puython was installed (in my case it was 2.7) and then installed the matching pip2.7 (Cygwin package python2-pip). So installed that and all its dependencies. (2) Opened a Cygwin terminal (not an X terminal, just mintty) and typed: $ pip install plotly


and watched some magic occur.

(3) Went to the Plotly website and created my (free) account. Went to my account settings and selected ‘API keys’. Could not see key — just looked like a row of dots! But hitting ‘Regenerate key’ gave me a new, visible one. Copied that text and noted my username.

(4) In Cygwin, (note, $is the Cygwin prompt, >>> is the python prompt) typed: $ python
Python 2.7.13 (default, Mar 13 2017, 20:56:15)
[GCC 5.4.0] on Cygwin

>>> import plotly

quit()


This set up the info needed for the local Plotly/Python installation to talk to the website where the graph will appear.

(5) Checked that this had worked out. Back at Cygwin prompt, in home directory, typed:

$cat .plotly/.credentials { "username": "DarrenG2", "stream_ids": [], "api_key": "<<your key here>>", "proxy_username": "", "proxy_password": "" }  (6) OK, looked good. Now, tested it by grabbing an example from the Plotly website. Created a file ‘plotly_example.py’ and pasted in some text copied from the website: import plotly.plotly as py from plotly.graph_objs import * trace0 = Scatter( x=[1, 2, 3, 4], y=[10, 15, 13, 17] ) trace1 = Scatter( x=[1, 2, 3, 4], y=[16, 5, 11, 9] ) data = Data([trace0, trace1]) py.plot(data, filename = 'basic-line')  (7) Then saved and ran the script $ python2.7.exe plotly_example.py
High five! You successfuly sent some data to your account on plotly. View your plot in your browser at https://plot.ly/~DarrenG2/0 or inside your plot.ly account where it is named 'basic-line'


Looked good, though they’ve spelled ‘successfully’ unsuccessfully.

(8) But where was the graph? Well, I was working in a basic terminal window. It sent the graph to the web, but then tried to open it using the default links, the text browser. So all I got was a blank screen (typed ‘q’ to quit links). There are a couple of options to see the graph — one is just to paste the given URL into Edge, Chrome, Firefox. Another is to tell Cygwin to look elsewhere for its browser…

(9) Edited my .bash_profile file in my Cygwin home directory and added these two lines:

$BROWSER=/cygdrive/c/Users/darren/AppData/Local/Mozilla\ Firefox/firefox.exe$ export BROWSER


This set up the environment variable BROWSER and pointed it at the firefox.exe file (non-admin install, so in an unusual place). I also ran these two lines in the terminal window to save me closing and reopening it.

(10) Repeated step (7) and — lo and behold! — a Firefox window popped up and the graph was in it!

Plotly graph in Firefox, after running the script in Cygwin.

Now, mastery of Plotly and Python is a much bigger project, but at least this offers the beginnings. Note also that the graph can be edited interactively within the webpage where it appears.

Plots away!

# Ghostscript and GSview without administrator privileges

I downloaded gs921w64.exe, and double clicked, but Win 10 wanted admin credentials to run the installer. I changed extension to zip and double clicked. Extracted contents to

C:\Users\usename\install\gs

Then the viewer, GSview. To: http://pages.cs.wisc.edu/~ghost/gsview/index.htm

Again, install wanted admin rights, even when I did not specify C:\Program Files.

Again, renamed to zip, and unzipped into

C:\Users\usename\install\gsviewtemp

Then went in there and double-clicked setup.exe

Created and then set install directory to be

C:\Users\usename\install\gsview

Unclicked ‘for all users’ since no admin rights. Ran installer; it did stuff, but said something failed. Still, tried to run gsview64.exe itself (found it in the install folder and clicked on the exe file); it started but said it cannot find ghostscript; ok need to set some variables/config stuff.

So, GSview was running, but crippled. Went into its menus.

Selected ‘Option’ → ‘Advanced configure’ and put in the correct locations for ghostscript lib and dll. For ‘Ghostscript DLL’:

For ‘Ghostscript include Path’:

(The fonts folder was not there; I just created it where GSview expected it. It’s empty.) Closed then reopened gsview64.exe; it opened without error messages. Opened a test file… (examples inside gs folder). Yep. OK, try printing to some writer… only found 3 devices… pdfwrite, mswinpr2 and djet500… where are others? Won’t worry for now.

Oh well, seems usable.

Added the ghostscript binary (bin) directory to my local user path. (See for example here for local path.) Might be useful to add the gs lib to the path as well. The lib folder is where a lot of the batch files (command line tools) live. Didn’t find any pfb files after the install (maybe that was the error the installer threw?)  so added the path to the type1 fonts in my MikTeX installation. Can’t hurt, probably won’t help.

Added the path to the GSview binary to my path as well, just so I can use it from the command line more easily.

Anyway, seems to work nicely.

Standard example file from Ghostscript, viewed using GSview installed without administrator rights on Windows 10.

Natch.

# Search insde Word, PDF, XML and other files—installing and using crgrep

I am an editor in a business that uses Micro$oft products, but I want to be able to use the Linux CLI tools with which I am moderately familiar. In particular, I want to be able to grep Word documents, and that’s a problem because the new Word file format chops the text up and zips it up and hides it away. I googled and read a bit about crgrep (‘common resource grep’). Here is my experience so far. Downloaded from https://bitbucket.org/cryanfuse/crgrep or https://sourceforge.net/projects/crgrep/ Created a subdirectory c:\Users\username\installs\crgrep and downloaded the zip file into it. Worked in Cygwin, hence the forward slashes and dollar signs in the following. This could also be done through the GUI or in a PowerShell or CMD window. Choice is a wonderful thing. $ unzip crgrep-1.0.5.zip
$cd crgrep-1.0.5/$ vim INSTALL.txt


OK, so it needs java. Does it need the compiler (probably not, but check…). In the crgrep folder, typed:

$grep -ir javac  Returned no results calling the javac compiler. So it looks like the program needs the runtime but not the development kit (JDK), so that’s good. It’s what you’d expect. Now, I have the wonderful ImageJ installed (works effortlessly in userspace), and it installs the Java runtime environment, JRE. Maybe I can use that. Now, according to the INSTALL.txt file, the JAVA_HOME variable that crgrep wants points at something like JAVA_HOME=C:\Program Files\Java\jdk1.8.0_xx  and my grepping told me that java.exe should be in %JAVA_HOME%\bin\java.exe In Cygwin, my ImageJ tree looks like: /cygdrive/c/Users/username/installs/ij/ImageJ/jre/bin Which meant I needed to set JAVA_HOME to be C:\Users\username\installs\ij\ImageJ\jre (Windows-style path) (that is, the variable points the directory with the bin directory inside it, not the bin directory or the binary file itself.) But first checked the version — needs 1.8. $ cd ../../ij/ImageJ/jre/bin/

$./java.exe -version java version "1.8.0_112" Java(TM) SE Runtime Environment (build 1.8.0_112-b15) Java HotSpot(TM) 64-Bit Server VM (build 25.112-b15, mixed mode)  OK. I installed in userspace (work computer, no root/admin access), so I went to my Windows account settings (given the various versions of Windows, I’ll assume a user can find their own account setting page) and (for Win 10; Win 7 is no doubt different) in the ‘Find a Setting’ box I typed ‘env’ for ‘environment variables’, and chose ‘edit the variables for your account’. Note that searching for ‘path’ turns up nothing. It’s a little trick! Added an entry to the path: (Path → Edit → New) c:\Users\username\installs\crgrep\crgrep-1.0.5\bin and created a new environment variable: JAVA_HOME=C:\Users\username\installs\ij\ImageJ\jre And exited everything, esp. the command line window, then opened it again, typed SET in a CMD (‘DOS’) window to see if the new variables were present, then tried the command: H:>crgrep --help usage: crgrep [options] [] crgrep: Common Resource Grep. -a,--text Process binary files or database columns as if they were text --color Alias for 'colour'. --colour Colour-highlight matched text ('always', 'auto' or 'never'). Default colour is red, see USAGE.txt for other colour settings. -d,--database Database grep (disables file search) -h,--help Help -i,--ignore-case Ignore case distinctions in matched text -l,--list List resources which produce a match by name. No content is searched. -m,--maven Include Maven POM file dependencies in search --mood Only include matching content expressing a specific sentiment; values include 'positive', 'negative' or 'neutral'. Ignored if -l specified. Requires model data; see INSTALL.txt --ocr Enable OCR text extraction from images; requires tesseract libraries. See INSTALL.txt -p,--password Password required to access a resource, optionally used with -u -P,--proxy Proxy settings for http access, specified as [:] -r,--recurse Recursive search into resources -u,--user User ID or username required to access a resource -U,--uri URI to specify a JDBC database resource -V,--version Print the version number of CRGREP to the standard output stream --warn Display all warnings to standard output -X,--extensions Enable one or more extensions; comma sep. list such as -Xdebug,trace If is not specified, or is '-', read from stdin Please report issues at https://bitbucket.org/cryanfuse/crgrep/issues  OK, promising. I want it for grepping Word files, so let’s see… yes, it finds ‘data’ in the test file, and outputs a nice clean stream: H:>crgrep data text.docx text.docx:T:A key part of his research was the analysis of large datasets. As part of this he developed a software suite that included data modelling, reduction and correction techniques, and made of use the National Computing Infrastructure and other supercomputers. He enjoys the challenge of analysing and explaining complex data using words and carefully designed graphics. He likes Linux and the LATEXtypesetting system.  How about PDF? Converted the Word doc to PDF using the ‘Save as’ dialogue in Word. Then… H:\>crgrep data text.pdf text.pdf:1:36:datasets. As part of this he developed a software suite text.pdf:1:37:that included data modelling, reduction and correction text.pdf:1:40:challenge of analysing and explaining complex data using  Different output because of how PDF and Word chop up the text, but instances found in both cases. No need to specify a file type or anything. I have not explored the command line options, but I am already finding the program useful — for example, when I want to find multiple instances of multiple expressions (say acronyms or references) in multifile projects. Kudos. Just grepping around. # ReactOS on VirtualBox: No need for step-by-step instructions This is so simple there’s no need for step-by-step instructions, but I kept notes so I might as well post them. ReactOS 4.5 on VirtualBox 4.3.x on Debian 8.x. Not on VB5.1 because the older versions are what the Debian repo provides. (1) Installed VirtualBox; $ apt-get install virtualbox dkms


Host is 32 bit Debian 8.4 Netbook with 1 GB RAM and 250 GB HD. Low spec! (Atom N550)

(2) http://www.reactos.org/download and downloaded both disk images; starting with iso rather than LiveCD. Apparently should be able to use guest additions from Win 32 bit, 2003-era. Unzipped the images.

(3) Ran VB; selected ‘New’.

(a) Put in details — Name, Windows, 32 bit 2003.

(b) 512 MB RAM (default in this case)

(c) 20 GB HD.

(d) VDI format is fine.

(e) Dynamic is fine.

(4) System. Enabled PAE/NX.

(5) Storage — put the Reactos ISO in the virtual drive.

(6) Boot.

(7) Let install run:

(a) Chose language

(b) Pressed enter a bunch of times. I chose to do a full format not a ‘quick’ one.

(c) Waited… … … … … …

(d) Chose default to put OS in C:\ReactOS

(8) Removed cd rom image from virtual drive. (Devices menu).

(9) Rebooted.

(a) Watched as it interrogated the hardware and installed some devices.

(10) Rebooted again.

(11) It wanted to install a driver but could not. Oh well.

(a) Opened explorer in guest and double clicked on additions x86 exe file in the cdrom directory.

(b) Default install.

(c) Rebooted.

(13) Shared folders…

(b) In VB manager, added that folder in Share Folders menu. Did not click auto mount.

(c) Booted VM.

(d) Double-clicked ‘My netowrk places’ on the ReactOS desktop and there it was, called \\VBOXSVR\vbshare.

(e) In a terminal, needed to assign the folder a drive letter.

(f) Opened command prompt on guest and typed

C:\ net use x: \\VBOXSVR\vbshare


(g) Typed x:

(i) Typed some crap. yep, it’s there.

(j) Looked for the file on host system. Modified it.

(k) Saw modifications in guest and host. OK, that works.

(l) I’m not going to bother automating it, I’ll just put a readme on the ReactoS desktop.

(14) Done, as far as I can see. Looks pretty good.

Having said that, all the applications I wanted to be able to run can run on wine.

Still, seems to work.

Wine.

# CAPS LOCK disable on Windows without admin rights

Lots of sites tell you how to disable/remap CapsLock. But what if you don’t have administrator rights? Most of them tell you to pry off the key. Well, instead, I went to:

Here is an extract, which I put here just in case the original site vanishes, as sites sometimes do:

There’s a duplicate of the keyboard mapping registry key under HKEY_CURRENT_USER, which non-administrators can modify, and it appears to behave exactly like the key under HKEY_LOCAL_MACHINE.  So, for anyone in a similar position, here’s the registry key to modify:

HKEY_CURRENT_USER→Keyboard Layout→Scancode Map =
hex:00,00,00,00,00,00,00,00,02,00,00,00,1d,00,3a,00,00,00,00,00

Here is a screengrab of the .reg file:

Worked a treat on Windows 7, but it did not work on Windows 10.

Hmm…Code for conversion of CapsLock to Shift is:

00,00,00,00,00,00,00,00,02,00,00,00,2a,00,3a,00,00,00,00,00

Codes explained here:

https://www.experts-exchange.com/articles/2155/Keyboard-Remapping-CAPSLOCK-to-Ctrl-and-Beyond.html

But why it does not work in Windows 10 I don’t know. I did try it on a work desktop machine (that’s why I don’t have admin rights, ‘cos it’s a work machine), so perhaps it downloads registry files on logging in? Does that make any sense?

Right now I don’t care enough to find out, but I’ll look into it at some point in the future.

So there.

# Another Font for a Very Specific Purpose

I have been reading stuff on my HP200LX palmtop using VR, the Vertical Reader.  It basically turns the LX into a pretty useful book reader — ASCII only.  You have a single column of text, rather like a newspaper column. It’s most excellent. It comes with search, bookmark and various customisation facilities.

However, I found the fonts that came with it just a bit too small. I decided to make one of my own, which is at an old post here, but it went too far the other way and is too wide. So I decided to take that font and narrow it a bit — make a condensed version, in the correct parlance. Thus:

The two fonts are shown below. The comments about the design philosophy in the earlier post remain valid; but the new one is I think just as readable and gets quite a bit more text on the screen.

‘djgtry2.vfn’

Using the font ‘djgthin.vfn’.

The new font is available at DSPACE, along with the earlier one. The file to download is DJGTHIN.VFN.zip.

For what it is worth.

# Impressions of wine

Wine is a mighty thing. Wine is a project to allow Linux (and Mac OS) users to run Windows programs.  It does not emulate a Windows machine, the way, for example, DOSBox emulates the hardware that DOS runs on or that VirtualBox (VB) does on a much larger and more complex scale.  It is more like an interpreter. The website calls it a ‘compatibility layer’. What that means for us non-experts, is it takes Windows’ instructions, translates them into Unix equivalents, then passes them on. This is a less flexible approach than simulating hardware (it is specific for Windows, for example, where a VM can run any number of operating systems) but it is much faster and allows excellent seamless integration with the Linux environment.

I have used Wine on and off for years, but I am not a regular user. I use VB to run a Windows 7 VM on my main workstation, because I have to work with people who use Microsoft Office and various add-ins like MathType, and at the time when I set the VM up it was probably the best solution.

I’m not so sure now.

I have an old CD of MS Office 97. I recall trying to install it under Wine a few years back, and it was not highly satisfactory. Word threw some funny errors, and I could not type into Excel. But that was a few years back, and I use Debian on my desktop, which is not renowned for using the latest versions of packages.

So I thought I’d try it again.

I have a Netbook running current Debian, which is a lot newer than the ‘old stable’ I have on my workstation. I have a USB CD drive, so I gave it a lash.

Brilliant.

Plugged in the CD drive. It appeared in the file manager. [Caja — I use MATE, which I think is a great example of a FOSS project. Dissatisfaction with where the Gnome desktop was going (when it switched from Gnome 2 to Gnome 3) prompted people to get together to continue to refine Gnome 2. The result is a desktop environment which is very congenial for us slightly older users who first saw a GUI in the 1990s and reacted violently when Microsoft introduced the ribbon, for example. Now users can choose between Gnome and MATE, and everyone has more options.] I then opened a terminal and went to the CDROM subdirectory (in this case, at /media/cdrom) and ran:

/media/cdrom \$ wine autorun.exe

or whatever the installation program was called. Wine opened it like a native Linux application, installed the program (the psuedo-Windows hard drive is hidden away in .wine/drive_c of the user’s home directory).

It appeared in the ‘Other’ menu under the MATE Applications menu. So did a bunch of other stuff; it seemed to generate menu entries for all sorts of Windows executables that I did not want to use.

But that’s OK. Installed and ran Mozo, the MATE menu editor, and turned off all the entries I didn’t want, and moved Word and Excel to the Office category, and bingo I have Word and Excel (97, admittedly) running like native applications, almost no effort required.

Found an old zip file of Rietica1.7.7 (32 bit) on my hard drive; that installed perfectly as well. The Rietica website only hosts the new 64 bit version; I’ve not tried that.

Don’t know if I’ll even use Word and Excel, but the jump in the quality of the experience compared to Wine a few years ago shows how it’s a vibrant, massively useful project. A great solution.

Older tech.

# Add LibreCaslon (to name one) and Computer Modern (to name two) to Word

Not much really.

Now, if you do not have admin rights it is more interesting:

• Right click.
• Swear.
• When asked, select ‘Local — install for current user’ or similar.
• Finish installing.
• Use the Explorer to go to: C:\Users\username\PortableApps\PortableApps.com\Data (‘username’ is the login name of the user installing the software).
• Create a ‘Fonts’ folder in there.
• Put the OTF files into this folder.
• Start the Portable Apps Platform (if no shortcut/menu entry is available, go to C:\Users\username\PortableApps\PortableApps.com and run PortableAppsPlatform.exe). If it was started during installation, stop it and restart it.
• Open Word, say, and LibreCaslon now appears in the fonts menu.
• Close the Portable Apps Platform and it will not be accessible, though Word might still list it.
• Add any other fonts you like this way, but they’ll only be available while the Portable Apps Platform is running, and you’ll need to stop it and restart it to make them appear. On the other hand, installation/removal is really simple; to uninstall, turn off the platform and remove from the Fonts folder!

Lots of other great applications (LibreOffice, gnumeric, GIMP, all that) are available through the Portable Apps Platform.

Oh, Computer Modern is at https://www.fontsquirrel.com/fonts/computer-modern and https://www.ctan.org/tex-archive/fonts/cm-unicode/fonts/otf.

Meh.