lab 9

wow, i definitely learned a great deal during the course of this lab! first of all, i had to learn how to perform linear regression equations all over again. i had to perform similar equations during high school while working with graphing, but it had been awhile. i learned that calculating all of those things could be tedious and time-consuming. also, i learned that excel really does make data manipulation and data analysis much easier than doing it by hand. once i had completed the first exercise, i was able to move through the second application rather quickly. excel is a wonderful tool once you learn how to use it properly.

Excel stuff

I actually enjoyed this lab. Excel wasn't as bad as I thought it would be! I can definitely see how it would help to organize and manipulate large chunks of data.

logic gates

task 2 truth table:

A B Out
-------
1 1 1
1 0 0
0 1 0
0 0 1

This circuit is a biconditional and it functions as equivalence, the circuit is only true when the inputs are the same.



task 3 truth table:

A B Out1 Out2
--------------
1 1 0 0
1 0 1 1
0 1 1 1
0 0 1 1

They are the same and Demorgan's Law holds true.

Binary and such

the binary number 110010101, converted to decimal, is 405. the number represents 1+4+16+128+256=405. you take the right-most number and apply 2 to the power of 0, which leaves 1. you then add that to the next number 1, multiplied by the appropriate power of 2, which would be 2 to the power of 2, or 4. and so on.
the decimal number 529, converted to binary, is 1000010001. the easiest way i know of to convert decimals to binary is to divide the number by 2 until you get to 1, using "remainders" instead of decimals. for example, 529/2=264 r 1, then 264/2=132 r 0, and so on.
in positional number systems, the value of a number is based on its position in the string of numbers, and the base number explains how much the numbers, as they progress to the left, are multiplied by. non-positional number systems do not give a value to the different numbers, instead simply assigning them the number "face value" that is understood in conventional terms. for example, to represent the number "x" in a non-positional number system would require "x" amount of figures. this is not as efficient as a positional number system for representing large numbers.

Unix Commands

The work with Unix was very interesting. I have never worked directly with an operating system before, so it was a new experience for me. The "whoami," "who," and "finger" commands were interesting to mess with. It's cool to realize that there is so much information listed on computers about so many people, and the finger command allows you to view information on other users you find on the system. I couldn't find the equivalent to the finger command for Windows/DOS. The "clear" command ended up being quite useful for me because I hate to have the window too cluttered, yet I don't want to lose any of my work. In DOS, the command for clear is "CLS." The "cal" and "date" commands were neat to mess around with because they can display virtually any calendar for any date in history. In 2010, my birthday falls on a Thursday. In DOS, the command for date is "DATE" or "TIME." The "pwd" command ended up being very useful for me while i was going through and learning how to navigate through the different directories. It was useful because it allowed me to keep track of where I was at any given time, and to make sure I made it to the directory I wanted when I navigated away. In DOS, the command for pwd is "CHDIR."

Chapter 6

I found chapter 6 to be quite enlightening, like all the other chapters have been as well. I keep finding out that I knew a little bit about computers and the way things work, but I had barely scratched the surface in determining how things work specifically. I first noticed the "collaborative filtering" phenomenon while buying cd's on Amazon.com. I noticed that, after making a purchase, the website listed several cd's, books, and videos that were listed as "suggested." I was informed by the website that, "other people who bought this cd also liked..." and then I was introduced to a list of artists I hadn't even considered before. I actually discovered a couple of new musicians and cd's because of this feature. Moreover, I then noticed that each time I visited Amazon and conducted business, the website suggested more and more items and seemed to be customizing itself to show things that were suited to my likes and interests. In a somewhat scary way, the website generated a personality profile of me, the specific buyer.

This type of information storage and referral is very useful in my opinion. The world is an enormous place filled with copious amounts of things to experience. The World Wide Web is similar in that it contains vast amounts of information. Navigating around can become quite a chore, and often people begin to feel that they don't even know where to begin to look. Collaborative filtering offers people the benefit of seeing the paths that other people have taken so that they can begin to find their own way.

"Modeling the World"

i thought that the modeling lecture was very straight-forward and made sense of the phenomenon of creating models to represent reality. according to the lecture, the first thing that must be done when creating a model for something is to study the thing being modeled and figure out the important processes that must be explained. it is not enough to simply create a carbon copy of the thing as a model, it must explain what the thing does.