Thursday, February 26, 2009

Spending to make...

While it's a fairly common and reasonably accurate maxim that you have to spend money to make money, I find myself wondering if the same is true of energy. To reword and disentangle the metaphor: Can you save energy by using energy?

Here's a my train of thought: You have curtains in your house. It's possible to fit a motorised unit and automate the opening and closing of the same. This would same ostentatious, lazy and wasteful. To have a computer, sitting, always on, in your house, which decides when this should happen would seem to increase these negative factors.

But...

During winter, you try to close the curtains to keep heat in. Doing this early means you miss out on daylight and, furthermore, you have to turn on artificial lights. Doing this too late means that you loose heat through the windows. There's is probably a converse example in hotter climates than this, in which your house gets too hot in the middle of the day if you don't close the binds, meaning you have to turn on the air conditioning.

So then, at what point does the energy used to run the computer become a good investment? What if it has sensors inside and outside in order to measure the temperature gradient, and so it can choose the best time to close the curtains? What if it also manages your heating? What if it intelligently turns out the lights in rooms you're not in? Reminds you that you turned the oven on but haven't actually put anything in it... Makes damn sure that you get out of bed in the morning... and so on...

Tuesday, February 24, 2009

Call by the what now?

Some not work related computery bits and pieces have been percolating around my head for some time now. I think we should talk about them for a while. That is: I'll talk. You listen.

I'm probably going to write a couple of more techy blogs, all loosely interrelated. I am going somewhere with them, but I'm not entirely certain as to how much of this journey I will share with you.

First of all, I'm going to talk about the fairly simple computer related concept of "Call by reference" versus "Call by value". This is fairly basic computer science (though I wish they'd taught it properly earlier on in my course). It's possible (probable, even) that this example (or variations of it) has been used a thousand times before. I'm not going to go look for one (or the absence of one), I'm just going to write down my own particular take on it. I assure you that any plagiarism I'm about to commit is in no way deliberate. So, without further ado...

Let's say you want to send a specific piece of information to someone via email. Let's say it's part of today's featured article on Wikipedia (William I of Orange, at the time of writing). In today's connected digital world, you have too main options. First of all, you could send them the information itself, like so:
William was born in the castle of Dillenburg in Nassau, present-day Germany. He was the eldest son of William, Count of Nassau and Juliana of Stolberg-Werningerode, and was raised a Lutheran. He had four younger brothers and seven younger sisters: John, Hermanna, LouisMary, Anna, Elisabeth, Katharine, Juliane, Magdalene, Adolf and Henry.

There are several things your recipient can do with this. They can read it. They can edit it, but this will only edit their local copy. The original remains unchanged. If they want to request that a change be made, they can, however, edit it and send it back to you. This is "calling by value."

Your second option is to send them a link to the information:
http://en.wikipedia.org/wiki/William_I_of_Orange#Early_life

This, again, allows them to read it. They have to follow the link to the information it points to first, though. This time, if they make an edit (this being wikipedia) they actually are changing the original copy. They can also see what other information is around it, and if they feel so inclined they can change that is well. You might consider this to be an undesirable consequence. This method has the aditional advantage, however, that you did not have to take the time and effort to make a copy, and the amount of information you had to actually send is significantly smaller. This is "calling by reference."

If you deal with this sort of thing on a day to day basis, you may well be aware that when you do this sort of thing in a computer program you have another option. You can send a constant reference, which would be analagious to sending a link to a website the recipient has no write access to. For example:
http://www.britannica.com/EBchecked/topic/644041/William-I

My Bloody Valentine 3D <= 15 Words

Prepare to be confused, scared, and impressed by this surprisingly well made remake.

W <= 15 Words

It's well written, well acted, well made. But I just can't understand: why?

Choke <= 15 Words

It's a horrible cliché, but I'm afraid the book really is a lot better.