пятница, 22 октября 2010 г.

WolframAlpha and why I love its widgets

I am trying out new Capabilities of the Wolfram Alpha engine. Well, it is not that complicated as Mathematica, but still very useful, especially the new Widgets feature.

Let's learn by example. I need to have some easily accessible tool to recalculate lattice parameters from hexagonal to rhombohedral setting. How do I do that?

Well, first of all, I go to developer.wolframalpha.com and register myself as a 'developer'. Next, I watch the tutorial demonstrating the process of creating widgets. Five minutes later I start to shape my own.
The principle is very simple. You create a formula, assign variables, shape your widget, make some style adjustments and .. it is ready!

If we take a closer look.. the formula behind the widget is simple. I take A and C lattice parameters for the hexagonal cell and recalculate them:

{ArcCos[(15*a^2-c^2)/(2*c^2+6*a^2)]/pi*180, Sqrt[(c^2+3*a^2)/9]} where a=[//number:${A}//], c=[//number:${C}//]

As a result I obtain two values: one of them is the rhombohedral angle (Degrees), the other is the rhombohedral lattice parameter. The only trick was to make WolframAlpha engine to reuse the variables c,a or to set the simultaneously. We set all of them by where a=[//number:${A}//], c=[//number:${C}//].
Is that simple? I believe it is!

Now, let us answer the question - why we need it. My reasons are simple. I need something online, so I do not have to crawl all over my folders trying to find the solution. It also saves me some amount of disk space and backup efforts, which are more annoying than lack of space.
WolframAlpha will never displace Mathematica, but this tool is indeed worth to use. The widget which performs a reverse transformation (rhombohedral to hexagonal) can be found here or below.
Good day to you!

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