Do something about it: www.stopspying.ca or www.openmedia.ca

About two months ago I bought a Solomon SL-30 from a1parts.com, the online store for A1 Electronics here in Toronto. I chose that station after a lot of research, despite not being familiar with the name. This review is not based on a series of cleverly designed test, but just my day-to-day use of the station for soldering connectors, wires and even a little PCB work.

I had been shopping around for a while when I decided to try the Solomon SL-30. I knew I wanted temperature control, a comfortable pen, easily to find tips and a good build quality. I had considered the Weller WESD51D, the Hakko FX-888 and the Edsyn 951SX SX-500D.

Summary

I’m really very happy with the station overall. I feel like I got good value for my money, and I got just about everything I wanted in a soldering station.

Pros

• Temperature setting and readout, very nice, especially for the price.
• Solid quality — a heavy unit with solid feeling construction. The temperature knob feels smooth and strong. I feel like this may be something that will be in my workshop for a lot of years.
• Tip and iron replacement seem readily available, even if the iron is swapped to Elenco brand. However, apparently Solomon has been around for a lot of years and is one of the biggest manufacturers in the world (according to Glen from A1).
• Really nice holder for the iron. I’m not a big fan of the wire coil ones, and because space is an issue for me, I also don’t want one of the huge ones that hold the iron and sponge (or brass) separate from the unit.
• Silicone coated wire on the iron, not that I can imagine ever burning my iron with itself.

Cons

I can really only think of one con:

• I really wanted a thin pencil-like iron with a super flexible (spaghetti-like) cord, but this one feels like most any cheap plug-in iron. In fact, it feels just fine in my hand, I just like the look of the smaller ones. The cord is a little stiff at first too. The silicone grip does occasionally slide down on my pen, but I just push it back up. I’m nitpicking really.

Deciding on the Solomon

The price of most other offerings, relative to the feature set really made the decision for me. Less than $100.00 got me a temperature controlled soldering station with a digital readout of both current temperature and set temperature.

I read a lot of reviews saying that the Weller had a cheap knob that broke, and basically that people who had owned Wellers from 40+ years back aren’t happy with the quality of the modern Weller products. Solomon seems to come out with new products, but the quality (from what I hear) is consistent. I was really tempted to get a Hakko, and I probably will some day, but there was just nothing for this price that could compete with the SL-30.

A serious consideration was the Elenco line of soldering stations, some of which seem identical to the Solomon offerings. The price of Elenco stations is a little less online, but shipping costs make it preferable for me to just buy it locally from A1 Electronics.

Impressions out of the box

A scanned image of the instruction booklet that came in the box with the SL-30. The reverse side seems to contain the same instructions in several languages.

Aside form the fact that the box looks like marketing material for a discount Chinese dish detergent, my first impressions were very good. Out of the box, the weight and build quality felt good, and everything was straight forward to set up.

Afterthoughts

It really just does what you expect. There’s not much more to say. The tips are very nice for the price, but the handle feels somewhat cheap. I’m going to be very picky on this point, however, because I really did want a station with a thin pencil-like handle and a very flexible cord. The Solomon is a little disappointing in that light, but there is really nothing to complain out. It is comfortable to use, even for hours at a time.

If anything ever happened and I had trouble getting Solomon parts, I believe that I can buy an Elenco replacement iron and tips (~$20.00 total) and it should be a drop-in replacement for the Solomon iron.

Overall…

I’m very happy with the unit, and I feel like I’m going to use it for a long time. I’m eventually going to replace it with a very expensive one, but that will be years down the road. And based on the build quality, I definitely feel that years down the road when I do replace it, I will be replacing a fully functioning Solomon.

There is a very unfortunate deadline (Wed 01 Sep, 2010, as I understand it). I am volunteering my time to help edit the grade 12 physics text. I will be trying to do as much as I can before this deadline. As a result, there there will be further delays in content being added to t-square, and the long overdue overhaul.

These textbooks have liberal licenses, and can be used to educate children around the world. The books can be downloaded, modified and printed without royalties. Governments can educate their children with these books at no cost but that of printing. Curious children who want to learn can download them an enrich their minds. This is exactly what the world needs!

I urge those with post-graduate degrees in science or math to step in and lend a hand. As learned members of the World’s small scientific community, what higher calling could there be for us than the inspiration and education of our children?

With exciting new features and many welcomed bug-fixes, Inkscape 0.48 is packaged to please. Although the new 0.48 instalment of Inkscape is yet to be released as of the time of this writing, I have experimented with a pre-release copy available for download on Sourceforge. Ubuntu users can install from Rico Tzschichholz’s PPA:


sudo add-apt-repository ppa:ricotz/ppa
sudo apt-get update
sudo apt-get install inkscape


Notably, this release marks the return of shorter release cycles, meaning that we can expect more frequent doses of fresh Inkscape goodness. I’m sure many of us are happy about this news.

First Impressions

Users aren’t bound to notice many differences upon initial load. Although there is a lot of refinement of the user interface (UI), there are no major design changes aside from artifacts of the new features. This is good, since the UI is very well designed already.

Users trying the latest Inkscape will likely find, as I did, that the new features and tweaks are best discovered as you begin working. Aside from the new menu entries, the first new feature that really struck me came about while I was trying to import a raster image. After I had dragged the file into my document, a new dialogue box popped up and asked me if I wanted to embed or link the image. Now, I can’t tell you how many time’s I’ve opened old documents to painfully discover that I forgotten to embed the images! This new dialogue is definitely a new point of refinement, and set the tone for what was to come.

New Features & Tweaks

There are too many features and tweeks to cover here, so I’ll be writing mainly about my personal highlights. The interested reader can check the release notes for the full list.

Spray objects tool

A screenshot featuring the Inkscape spray tool.

Overhaul of the text tool

A screenshot featuring Inkscape 0.48's redesigned text tool

A very welcomed item in the 0.48 release is the overhauled text tool. If you look at the screen-shot (right), you’ll see that the text-dialogue mostly looks the same, but if you look at the menu-bar for the text tool (at the top of Inkscape window), you’ll see a barrage of new options for controlling line spacing, kerning, superscripts subscripts, etc.

Still sorely absent from the font tool is the ability to control font-variants such as small-caps. This is a huge problem for most who does layout work in Inkscape. If I have a $350.00 font, I darn-well want Inkscape to be able to use the professional features. I’d like someone to let me know if Inkscape will support it if the XML file is manually edited for this. Last time I checked (about 2 years ago), it didn’t.

Cool new extensions

This release boasts a number of very cool new extensions. My favourites are:

• The new JessyInk extension for creating slides for presentations that are viewable in browsers — See my Tutorial Introduction to JessyInk.
• The new Web > Slicer extensions to slice web layouts into multiple images and help the HTML+CSS creation.
• The Modify Path > Pixelsnap extension that aligns rectangles and paths to pixel boundaries, to create sharp web and digital graphics. — This has been a sorely needed convenience function.
• The sphere extension which draws the globe as a collection of ellipses representing a sphere’s latitude and longitude lines.
• The Generate from Path > Voronoi Pattern extension which creates a random pattern of Voronoi cells (resembling the cell pattern in dry/cracked dirt).
• The Render > Barcode - Datamatrix extension which renders a DataMatrix 2D barcode, as specified in BS ISO/IEC 16022:2006.

LaTeX PDF export

The LaTeX PDF export function has me rather excited. Expect a tutorial soon.

I can remember making diagrams for my MSc thesis in Inkscape, and then having to use the LaTeX picture environment to manually nail down the coordinates for each an every text label that I wanted—one at a time. This is done so that the fonts in the diagram will match the fonts in the document.

Of course these days, I use TeXtext (check out my brief article on TeXtext) to simply generate the text and symbols. The font in TeXtext can be set in the preamble file that TeXtext can take as an option. One drawback to this method however, is that the text is now fixed, and if oned desires to change their document font then all of the text must be redone.

With the new LaTeX PDF export function in Inscape 0.48, Inkscape will do the grunt work for you. It will create a .tex file along side a pdf file for inclusion in your LaTeX document. The .tex file contains all of the text and placement information so that LaTeX will display the pdf diagram, and then use the information in the accompanying .tex file to draw and overlay the diagram’s text. GNUPLOT users will find this quite similar to GNUPLOT’s epslatex terminal.

Upgraded swatches

From the release notes:

Custom swatches can be created and used on a per-document basis. An “Auto” color palette will track swatches in the current document and allow them to be set and used. The use is “live” with changes to the swatch being applied automatically to all objects set to it. The swatches can also be gradients and not just simple colors.

As it stands right now, I don’t think this is working yet. I wrestled with the swatches for some time, but I could not even manage to add a simple colour (but it did let me add a gradient for some reason). I hope this works its way into the final release of Inkscape 0.48.

Rewritten node tool

During Google Summer of Code 2009, the node tool underwent an extensive rewrite boasting several new features. These are perhaps too numerous and detailed to describe here, but I can summarize by saying that the node tool functionality is improved and users can expect a cleaner and more productive experience. The most notable improvement is the ability to select and edit multiple paths at once.

The interested reader is encouraged to read about the node tool rewrite on Inkscape’s wiki page

Final Words

With new features that are both relevant and useful, the 0.48 release is the most powerful version of Inkscape yet. It is packed with welcomed tweaks and changes that improve the overall user experience and scratch a lot of old itches.

I expect to strongly recommend that everyone upgrades as soon as the official release is available. I would currently recommend that users upgrade non-production machines to the current pre-release to explore some of the new features. It’s definitely stable enough to use, as is.

The new Inkscape 0.48 pre-release is incrementally more sophisticated and stable than the current 0.47 is. Inkscape is currently one of the best examples of an open-source project, and the Inkscape community never fails to amaze me with their work. I’d like to thank all of the developers for their countless hours of effort that makes Inkscape one of my favourite pieces of software.

1. YOUTUBE – Stupid me was asking for a puppy when I was 10. If I had only known about these!
   
2. TECHCRUNCH – Attempt At P ≠ NP Proof Gets Torn Apart Online

   What happens when Twitter and online communities filter scientific discovery ahead of professionals? As we saw this week, a lot of fuss over a result that will ultimately be discarded into the dustbin of flawed mathematical proofs.

   Read more…

3. IDENTI.CA – A hilarious dent (identica tweet) from user, Luke Slater (reality):
   

   reality: Windows is easier than Linux, in the same way that crapping your pants is easier than going to the bathroom

4. YOUTUBE – Electrooculogram to play old-school Mario: Awesome!
   
5. CBC NEWS – Ont. parents suspect Wi-Fi making kids sick

   A group of central Ontario parents is demanding their children’s schools turn off wireless internet before they head back to school next month, fearing the technology is making the kids sick.

   Some parents in the Barrie, Ont., area say their children are showing a host of symptoms, ranging from headaches to dizziness and nausea and even racing heart rates.

   Read more…

6. LIFEHACKER – Top 10 Ways Your Brain Is Sabotaging You (and How to Beat It)

   An unexamined brain is a tricky thing to carry around. You’ve got unintentional biases, marketing weaknesses, “overclocking” issues, and all kinds of other mental bugs you may not know about. Here’s a helpful list of the mind’s weird ways.

   Read more…

7. LINUX JOURNAL – Oracle Delivers Friday the 13th Bad Luck to FOSS

   Despite personal beliefs, everybody treads a bit more carefully on Friday the 13th. But no amount of precaution could protect the Open Source community from the wave of bad luck that fell last Friday. Oracle finally lived up to the fears many have been afraid to speak.

   Read more…

8. LIFEHACKER – Embed Google Calendar on Your Linux Desktop
   

   [...] Here’s how to embed Google Calendar into a Linux desktop.

   Read more…
9. LINUX JOURNAL – Legal DVD Playback Coming to Linux?

   From nearly the beginnings of entertainment DVDs, Linux users in certain countries either had to break the law to watch their legally obtained media on their computer, boot a Windows system, or not use them. Many chose to break the law and install decryption software. Perhaps those days are over.

   Read more…

10. LIFEHACKER – Turn a Sheet of Paper into a Simple Flash Softbox
    

    If you’re looking to soften up your camera flash on the cheap—perhaps because you were startled to see how unflattering direct flash is—this clever softbox turns a sheet of office paper into a lightweight flash diffuser.

    Read more…

Sure, presentation slides are becoming passe in the business office. (And it’s about time too.) But in technical fields which require a lot of illustration and visualization, there simply is no better way to have an ordered discussion.

PowerPoint and alike place far too much emphasis on text elements and distracting effects and transitions. For my presentations, I usually use the beamer class in pdfLaTeX since two things are handled very well: math and vector graphics. But as my style has honed towards minimalism with attractive and illustrative graphics, I’m spending more and more time in Inkscape. Wouldn’t it be great to just create presentations in a vector graphics editor? Hannes Hochreiner certainly thought so. While a chemistry Ph.D student at Canada’s Dalhousie University, Hannes began developing a set of Inkscape extensions called JessyInk.

JessyInk, to be included in the next major release of Inkscape, adds functionality for creating slide-show presentations to Inkscape. The de facto output (and internal memory) format for Inkscape is SVG, which is a human-readable XML that can be rendered by all major modern browsers except Microsoft Internet Explorer. JessyInk embeds JavaScript within the SVG files adding the dynamic functionality required for presentations.

JessyInk gives users the ability to embed slide-transitions, text reveals, navigation, hot-keys, video embedding, mouse event handling and much more. It provides more than what anyone should need to create effective, clean, efficient and impressive slides.

What remains in this article is intended as an introduction to JessyInk work-flow. I’ll demonstrate the creation of a basic slide-show with text-reveals and navigation. I’ll build upon these fundamentals in later tutorials.

Files to download before moving on:

• Example slides for this tutorial
• Official JessyInk showcase presentation

Note: If you don’t already have JessyInk installed, I have a tutorial on installing JessyInk for Ubuntu, Linux and Windows.

Note: Of course, one may still need elegant mathematics in Inkscape. Click here for my article on TeXtext for math in Inkscape.

A word on viewing.

As you work along with this tutorial, it will be useful for you to preview your slides. Once you have saved your Inkscape SVG, open it with your browser. Each time you save your Inkscape file, refresh the browser window to view your changes.

When you are presenting, remember to make your browser full-screen (usually F11) so that the browser buttons don’t distract your audience.

JessyInk Basics

JessyInk causes your browser to render each layer in the SVG as an individual slide. This is how we can define many slides within a single SVG. To better understand the concept, download the example slides used for this tutorial. Clicking on the link should bring the presentation into your browser. Save the file to your hard drive and open it in Inkscape to get a closer look.

Elements common to all slides may be placed on the master-slide, which is a special layer that is rendered across all slides. For example, it is a good idea for the master-slide to contain your presentation’s theme and auto-texts for slide numbers and slide titles. We’ll cover auto-texts later in the tutorial.

If you are not already familiar with JessyInk, you should first download and explore the official JessyInk showcase slideshow which gives an overview of JessyInk’s capabilities and briefly discusses many of the functions demonstrated in this tutorial.

Let’s get started by defining our slide geometry and background colour: start a new document and press SHFT+CTL+D or File > Document Properties.

Fig. 1 - Document properties window showing document dimensions and background color.

Slide geometry

Before moving on, you need to choose the geometry of your canvas. It should depend on your intended target. If you plan that most of your audience will view the slides in their browsers, then I prefer 864×486, which has an aspect ratio of 16:9. Web browser rendering areas tend to be wider than tall due to the tool-bars and buttons adorning the browser window. So a wide aspect ratio will utilize more of the window. Also, 16:9 is a standard aspect supported by most projectors and many computer monitors made in recent years. However, if you know that you intend to present using a projector that has 4:3 aspect and aren’t worried as much about how it appears in a web-browser, then I suggest 640×480 or 800×600. Remember: vectors will scale so size isn’t important unless you will be using raster graphics in the slides.

Once you’ve chosen your slide geometry, enter the width and height in the appropriate text boxes in the Document Properties window. For this tutorial, I’ll use 864×486 (See Fig. 1).

Background colour

While still at the Document Properties window, we may also choose the background colour. Note that background colour is not going to be the colour of your slides; it’s the colour of the area around the slides if they don’t fill the entire browser window. You’ll see what I mean, but the idea is akin to the black bars at the top and bottom of a movie when it doesn’t fit your TV screen. For my example file, I’m going to choose a nice blue, #052b59ff.

The master slide

Press SHFT+CTL+L to bring up the layers dialogue or go to Layer > Layers. It is a good idea to have the layers dialogue open while using JessyInk since we will be working with layers a lot.

Fig. 2 - JessyInk's master-slide dialogue box with blank canvas in background.

Right click on Layer 1 in the layers palette and rename it to Master or something else meaningful. It’s going to become our master-slide. Go to Extensions > JessyInk > master slide and enter Master, or the name you just chose for your master-slide (Fig. 2). Once you apply, JessyInk will define the slide you renamed as the master-slide for the presentation. Anything on this layer will appear on all slides within your presentation.

To construct the basic backdrop for our slides, with the master-slide selected draw a rectangle and make it the same size as the canvas. Fill it as you wish and centre it on the page with align dialogue box (CTRL+SHFT+A). For my example, I’m going to use a simple white/grey gradient which is both simple and rich looking. Now as we create slides, this backdrop will appear on all slides.

Auto-texts: slide titles

Auto texts are text elements in the slide which are dynamically generated for each slide. For example, if we want to put the slide number or title on each slide, there is no need to manually number or title each slide. We can add a placeholder text and have JessyInk insert the proper text on each slide.

For our example, I’m going to put the title at the top of each slide. Since it will appear on all slides, let’s add it to the master-slide.

I’ll start by putting a dark rectangle across the top of the slide which will distinguish the titling text. Then, I’ll use the text tool (press t or select it from the tool palette) and place the simple text Slide Title on top of the rectangle.

Fig. 3 - JessyInk's auto-texts dialogue box inserting slide title.

We obviously don’t want the literal text, Slide Title to appear at the top of each page. In order to have the title automatically inserted instead, highlight the text block and click Extensions > JessyInk > auto-texts to bring up the auto-texts dialogue box. Select the radial indicator beside slide title and click apply (see Fig. 3). Now, when we add slides to our presentation, the title will appear in place of the text Slide Title.

You can be quite clever about using auto-texts for aesthetic effect. For example, in the screen-shot to the right, I have created a reflection and drop-shadow for the slide titles. Note: I realize that a reflection and a drop-shadow is stylistically overboard, but I’m making a point here. Remember: less is more. When presenting you always want to have maximum affect by minimal means.

Fig. 4 - I've added a drop-shadow and translucent reflection to the slide title, that will appear as the actual slide title during the presentation.

To make the reflection, simply duplicate the auto-text (highlight it and press CTRL+D) and then flip it vertically (press v) and then move the reflected text below the title text. Then open the fill and stroke dialogue (CTRL+SHFT+F) and set the fill to a gradient. Set the gradient stop colours to a grey and then a fully transparent grey. Using the gradient tool (press the g key or select it from the tools palette) move the gradient end-points until you get something that looks like a reflection.

To make the shadow, duplicate the title text again and set the fill colour to black. Using the pg dn (page down) key, drop the black copy of the title text behind the white copy. Open the fill and stroke dialogue and add a Gaussian blur and reduce the transparency until you get something you like.

Titling slide

Fig. 5 - Creating Title Slide layer.

Well, we’re all dressed up! Let’s go out. There’s no real trick to adding slides. Just add a new layer by clicking the + symbol on the layers palette (Fig. 5). The only issue is that when we are making a titling slide, we might not want the master slide showing through. No big problem here, just cover it up. To make my titling slide, I’m going to copy the background gradient from the master slide and paste it onto the title slide. Now just make it look as you wish.

Revealing bullet points: build-in effect

Think before you include bullet points. There are very few cases where they are actually justified. You never want your audience to read while you’re trying to talk to them.

Fig. 6 - The effects dialogue for JessyInk applying a fade-in reveal for the second bullet point. Also note the vertical rules for aligning bullets and text.

That said, one of the most commonly seen formats for slides is the step by step reveal of bullet points. This is easily done in JessyInk. First, set up your bullet points. There’s no convenient tricks here: just use the text tool to make text and draw the bullets. I do recommend using a couple of vertical rules and a horizontal rule (see Fig. 6) to align the bullets and text. Use the align and distribute dialogue to arrange things nicely (CTRL+SHFT+A).

Once you have created at least two bulleted text elements, select and group (CTRL+G) each bullet with its corresponding text so that each bulleted text element is only one object. We want this so that we can apply effects to the text and bullet simultaneously instead of having to do it separately for text and bullets.

Now we can program the reveal for each of the elements. If you want to have an element visible when the slide first appears, leave that one alone since it will of course be visible by default. Select the first element that you want to be revealed and click Extensions > JessyInk > effects to invoke the effects dialogue (Fig. 6). I’ll explain the settings in the next paragraph but for now just copy the settings from the last figure. That is, order: 1, duration: 0.4, type: fade. Leave the build-out effect settings at default values. Click apply when finished.

The two effects available in the effects menu, build-in and build-out, reveal and hide elements respectively. The order will indicate 1st, 2nd, 3rd, etc to be revealed. So for the first element you want to be revealed, set the build-in effect by changing the type radial selector from none to one of appear, fade or pop, and set the order to 1. The next item you want revealed should have an order of 2, and so on.

Slide transitions

Slide transitions are also something that should be used with reservation. Transitions are applied so that as the slides progress, new slides are brought onto the screen with an animated effect.

Create a new layer and put some text on it. I’m simply calling the new layer Slide transitions and placing the text This slide should fade in smoothly…

Fig. 7 - JessyInk transitions dialogue.

To create the slide transition, go to Extensions > JessyInk > transitions. In Fig. 7, you will see my settings. Simply input the name of the slide which you want to apply the transition to and select the animation type (fade, pop, etc). You can program a transition-in and transition-out. The transition-out is only needed if you would like a smoother transition. For example, if I am using the fade transition, and I only set transition-in effects, then when I change slides my current slide disappears and the next slide fades-in from nothing. If I set my slides to transition-out then as I go to a new slide, the current slide fades out as the new slide fades-in, creating a nice smooth transition.

Bringing it all together

I think by now I have covered the basics which should suffice for most presenters needs. I’m going to create one last slide which emcompasses most of the concepts covered so far.

I’m calling my last slide Conclusion. After it’s created, I’ll start by applying a slide transition. I’m going to apply a fade-out on the second to last slide and a fade-in on Conclusion to get a nice smooth fade. I know I’m using a lot of fades. I want to leave it to the user to explore the other animation effects.

Now, I’m going to create several blocks of text. I do not want all of the blocks to appear at the same time. In fact, I only want one block at a time to appear, so this means that as one text element fades in, the previous one needs to fade out.

As before, pick one of the blocks of text to be present when the slide comes in. This means it will have no build-in effect. Open the effects dialogue by clicking Extension > JessyInk > effects. The build-in type should be set to none, but set the build-out to fade, the order to 1 and set the duration to 0.3. Now click apply.

Fig. 8 - Screenshot of effects configuration with my overlapping text in the background.

Select the next block of text that you will want to appear. Set the build-in to fade with duration 0.3 and order 1 and set the build-out to fade duration 0.3 and order 2. Select the next block and set the same options with build-in order 2 and build-out order 3. Hopefully you can see the pattern forming. We want the order of the fade-out to be one higher than the order of the fade-in (see Fig. 8). We also want the fade-out order of the previous text to be the same as the fade-in order of the new text. The effect is quite interesting. Now use the align and distrubite dialogue to center all of the text on top of eachother.

Conclusion

Thank you for reading and following along. I hope this tutorial was useful. There will be more to come on more advanced JessyInk and Inkscape topics. If you have a request, feel free to contact me, and I’ll be happy to consider creating a tutorial for your need.

The main security threats to students are identity theft, data loss and data theft. Identity and data theft are both becoming growing problems around Canadian campuses… So what steps should students be taking to make themselves a much harder target?

What follows is a list of reasons (and maybe even suggestions) for why you should know Python.

• Python is executed, not compiled. This immediately allows for rapid development, removing overhead of doing certain tasks manually. Once you become familiar with Python, you will tend to write codes to perform tasks that you perhaps would have otherwise done by hand.

  Executed languages have a reputation for slow execution. Few would dare do large Fourier transforms or matrix inversions in an executed language, but Python remains viable. The overhead for memory operations is low and thanks to NumPy (more on Numpy and SciPy in a moment) array slicing is also very efficient. In addition, Python integrates very well with binary codes. So use a well proven binary code for the heavy lifting but use Python everywhere in between.

• 

  A screenshot of SciPy at work, finding the maxima of Bessel functions.

  Python is a very mature language and almost anything fundamental you might want to do is implemented in a library or module. For numerical work, check out NumPy and SciPy. NumPy introduces a powerful N-dimensional array object and tools for integrating C/C++ and Fortran code. It also has built-in linear algebra, Fourier transform, and random number capabilities. SciPy builds upon NumPy adding even more useful tools such as numerical integration of functions, discrete sets, ODEs and PDEs and optimization tools. From the SciPy website:

  The SciPy library depends on NumPy, which provides convenient and fast N-dimensional array manipulation. The SciPy library is built to work with NumPy arrays, and provides many user-friendly and efficient numerical routines such as routines for numerical integration and optimization. Together, they run on all popular operating systems, are quick to install, and are free of charge. NumPy and SciPy are easy to use, but powerful enough to be depended upon by some of the world’s leading scientists and engineers. If you need to manipulate numbers on a computer and display or publish the results, give SciPy a try!

• Matplotlib for visualization, 3D, VTK, and integration with GNUPLOT. Visualisation is a key part of any scientific workflow. I personally enjoy GNUPLOT, so I tend to use gnuplot.py for a good part of my plotting needs. You should also investigate matplotlib, an incredibly powerful plotting library which is very user friendly and integrates seamlessly with NumPy and SciPy. For good integration with LaTeX, one can also look at PyX. For 3D visualization, don’t forget about VTK, the Visualization Tool Kit. VTK has Python bindings. If you’re particularly ambitious, Python even has OpenGL bindings. Whatever your visualization needs are, Python can handle it.
• Once you’ve spent some time writing Python code, you’ll likely come to apprciate how clean and readable the code is. This can save you time and effort later when (A) you look back at your own code with nary a notion of how it worked in the first place and (B) when you want to share your code with others.
• And you are likely to share code with others, since Python code is very portable. Python is cross platform, so you don’t need to worry about sending code between colleagues: Windows, Linux and BSD users alike. If you’re a Windows user, it means you can develop code on your Windows machine and simply upload the code to a cluster when you’re done and run it without revisions or recompiling.

I hope this has convinced you to try Python. The learning curve is rather gentle, and I’ll be writing tutorials in the coming weeks for performing standard tasks using Python. If I’ve convinced you to learn more, I’ll conclude with a few links to get you started.

• SciPy Course by Dave Kuhlman
• Handbook of the Physics Computing Course by Michael Williams
• Python for scientific use. Part I: Data Visualization by Anders Andreasen
• Python for Physics from University of Cape Town

GNUPLOT has a range of terminals that work with LaTeX, including a LaTeX terminal. If you’re using system fonts and XeLaTeX, then the pdf terminal can do a very nice job, but if you’re using fonts in your document that are installed with LaTeX, then only one terminal can suit my standards: the TikZ terminal.

PGF and TikZ are a macro package and syntax layer (respectively) for creating graphics in LaTeX. The TikZ syntax is sophisticated and human readable. If you do a lot of presentation work with LaTeX, then it’s well worth your time to learn the basics. But we don’t need to know anything more about them to use the TikZ terminal in GNUPLOT.

The GNUPLOT installed by your distribution’s package manager probably doesn’t have this terminal. You’ll probably need to compile GNUPLOT from scratch, being careful to link to the LUA libraries since the TikZ terminal is built on the LUA terminal. This isn’t so bad, and I have written a tutorial to walk you through compiling the CVS version of GNUPLOT.

Standalone vs. Copy-and-Paste Output

The TikZ terminal has two modes of output. The standalone mode prints out a document that can be simply run through pdfLaTeX producing a pdf file that can be imported into your LaTeX document. The default mode of the terminal, however, prints out the text to generate the plot within a tikzpicture environment.

Both of these are useful depending on the size of your document and the number of plots you have. Compiling these plots within your document can take quite a bit of LaTeX’s memory, so if you have more than a few plots, you can actually exhaust the limit of TeX’s memory. You can expand TeX’s memory (not recommended), but this results in documents which take several minutes to compile. So make your choice.

Working with Standalone Output

So let’s try this out. From the command-line, make a new directory, cd into it, and run GNUPLOT. Type in the following code:

set term tikz standalone color solid size 5in,3in
set output "sin.tex"
set xrange [0:2*pi]
plot sin(x) with lines
exit

That code switches the terminal to tikz in standalone mode with colour and solid lines, and defines the plot size to be 5″x3″. Next, we set the destination of the output to be the file “sin.tex”. Then we set the range of the plot to be between zero and two-pi, and finally, we plot sin(x). Remember to exit GNUPLOT so that it finishes its output to sin.tex. Here is a listing of the sin.tex output file:

\documentclass[10pt]{article}
\usepackage[T1]{fontenc}
\usepackage{textcomp}

\usepackage[utf8x]{inputenc}

\usepackage{gnuplot-lua-tikz}
\pagestyle{empty}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{2mm}


\begin{document}

\begin{tikzpicture}[gnuplot]
%% generated with GNUPLOT 4.5p0 (Lua 5.1.4; terminal rev. 97, script rev. 96a)
%% Sat 17 Jul 2010 09:00:38 PM EDT
\gpsolidlines
\gpcolor{gp lt color border}
\gpsetlinetype{gp lt border}
\gpsetlinewidth{1.00}
\draw[gp path] (1.196,0.616)--(1.376,0.616);
\draw[gp path] (12.147,0.616)--(11.967,0.616);
\node[gp node right] at (1.012,0.616) {-1};
\draw[gp path] (1.196,1.279)--(1.376,1.279);
\draw[gp path] (12.147,1.279)--(11.967,1.279);
\node[gp node right] at (1.012,1.279) {-0.8};
\draw[gp path] (1.196,1.943)--(1.376,1.943);
\draw[gp path] (12.147,1.943)--(11.967,1.943);
\node[gp node right] at (1.012,1.943) {-0.6};

...

  --(8.386,1.171)--(8.497,1.060)--(8.607,0.961)--(8.718,0.874)--(8.829,0.798)--(8.939,0.736)%
  --(9.050,0.686)--(9.160,0.650)--(9.271,0.626)--(9.382,0.616)--(9.492,0.620)--(9.603,0.636)%
  --(9.713,0.666)--(9.824,0.710)--(9.935,0.766)--(10.045,0.834)--(10.156,0.916)--(10.267,1.009)%
  --(10.377,1.115)--(10.488,1.231)--(10.598,1.359)--(10.709,1.496)--(10.820,1.644)--(10.930,1.801)%
  --(11.041,1.967)--(11.151,2.140)--(11.262,2.321)--(11.373,2.508)--(11.483,2.701)--(11.594,2.898)%
  --(11.705,3.100)--(11.815,3.306)--(11.926,3.514)--(12.036,3.723)--(12.147,3.933);
\gpcolor{gp lt color border}
\gpsetlinetype{gp lt border}
\draw[gp path] (1.196,7.251)--(1.196,0.616)--(12.147,0.616)--(12.147,7.251)--cycle;
%% coordinates of the plot area
\gpdefrectangularnode{gp plot 1}{\pgfpoint{1.196cm}{0.616cm}}{\pgfpoint{12.147cm}{7.251cm}}
\end{tikzpicture}
%% gnuplot variables
\end{document}

Now, run pdflatex sin.tex, which should produce the file sin.pdf. You can open sin.pdf to check it out, and notice that the font is Knuth’s Computer Modern Roman, which is the default in TeX/LaTeX. If you want to, you can now use the standard \includegraphics{sin.pdf} from the graphicx package from within a LaTeX document to include this plot in your document.

If, however, you use fonts other than the default, you need to take one more step to be sure that you use those fonts when compiling your standalone plots. The TikZ terminal accepts the header option which allows us to specify some extra code in the preamble of the standalone document. For example, I often use the txfonts package, so in gnuplot, I would have

set term tikz standalone color solid size 5in,3in header "\\usepackage{txfonts}"

Notice the double backslash (\\) above. This is because we need to escape the slash and other special characters. Take a look at the resulting output, and notice on line 4, we have our new font specification.

...
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{2mm}
\usepackage{txfonts}


\begin{document}
...

Non-Standalone Output

If you don’t specify standalone to the terminal, then by default it will output code that you can simply output to a tex file, and \include{file.tex} in your document, or straight copy and paste directly into your document. If you do this, you will need to include, in the preamble of your document:

 \usepackage{gnuplot-lua-tikz}

Let’s try an example. We can use the example from the last section to generate sin.tex, but without the standalone declaration:

gnuplot> set term tikz color solid size 5in,3in
Terminal type set to 'tikz'
Options are 'color solid'
gnuplot> set output "sin.tex"
gnuplot> set xr [0:2*pi]
gnuplot> plot sin(x) with lines
gnuplot> exit

Now execute the above code in GNUPLOT, then create another .tex document with the following code.

\documentclass{article}
   \usepackage{gnuplot-lua-tikz}

\begin{document}
Hello World!

There is a plot up top!
\begin{figure}
   \include{sin}
   \caption{TikZ plot from GNUPLOT!}
\end{figure}
\end{document}

Compile this code with LaTeX or pdfLaTeX and you should get a document which says Hello world, and has the floating figure.

Final Words

Of course, the terminal can handle much more complicated figures, but this should get you started. If you’d like more resources and tools for TikZ, click here.

To get those tasty beverages cold in a hurry, here’s a neat trick. Fill a bucket, basin, whatever, with cold water, and dump in your drinks and as much ice as you can find. Not a very clever trick, eh? Here’s the trick: add a bunch of salt. The salt lowers the melting temperature of the ice, allowing the water temperature to drop below zero, pulling the heat out of the drinks faster.

The Physics

If you’re interested in the details of how this works, read on. If you just want to use the tip, go cool off some beer.

There’s a few concepts in play here, and we’ll go in order of scale. First, it’s obvious that the colder the water is, the faster we’ll cool down the drinks. That’s seen most simply in Newton’s law of cooling,

which tells us that the exchange rate of heat, , between the beverages and the water is proportional to the difference in temperature, , of the beverages and the temperature of the water.

But why does salt lower the melting temperature of the ice? That has to do with the molecular structure of both. Table-salt is a crystal of sodium and chlorine. During the chemical bonding of these atoms, they exchange an electron, making each atom in the crystal an ion, with a positive or negative charge. Water, while being electrically neutral, is a polar molecule because the electrons have a higher density on top of the oxygen atom, and low density around the two hydrogen atoms. This separation of the charge results in an electric field.

When water freezes into ice, it forms crystals where the positive poll (the hydrogen atoms) of one molecule are attracted to the negative poll (oxygen atom) of the next, and so on. The ions from the salt interfere with the interaction between the water molecules making it more difficult for the bonds to form making ice crystals. This has the effect of lowering the melting temperature of the water.