Week 4 Comments


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Week 4 Comments

Comments on Week 4 here, please!

Do you feel comfortable with the basic ideas of building a collage?
Does the basics of physics and psychphysics (psychoacoustics) of sound make sense?
Do the basic operations on sounds make sense?

Thanks!

I don't know if i am the only one, but i thought i understood what was going on until today. i am really confused and don't really understand the collage thing. also, the midterm review appeared much harder than the things we have been doing in class.

When are HW 1 grades going to be posted?

By recitation Thursday.

Is it possible to have 1.5 for a pixel?

i agree with the first comment. I was lost today and Friday. The whole copy thing is blowing my mind.

Add the pre-quiz is over my head as well. Can anyone help at all?

Pre quiz question: the "if distance(pxcolor, lightblue) < 30.0" line is stumping me....Any advice anyone. i have two or three ideas of what to do w/ the 30 but I'm not sure if I can post my ideas....TA please let me know if I'm allowed to...thanks

Absolutely – post away! Mark Guzdial

I'm also a little confused about the pre-quiz. I remember the example from class, but i'm having such a hard time with one line. What can we post on this and can our TA's help???

It is really hard to complete the Midterm Exam review becasue I am having trouble finding help in the book, the slides, or in my notes. It seems like it is asking us to apply concepts we don't really have a grasp of (at least in the first question).
What to do if you don't understand a program?

If the question above is if a color component of a pixel can be 1.5, the answer is no. It has to be an integer between 0 and 255. For help on the distance function, see page. 123 and pages 145-147. Remember my advice on the first day of class: TRY EVERY EXAMPLE WE DO ON YOUR OWN! Yes, you can get help on the pre-quiz from wherever you want. You just have to learn it well enough to do the same kind of thing on your own tomorrow. Mark Guzdial

Do you consider 30 to be a number less than the distance of 30 to 0? (That may not make much sense-sorry.)

30 is not less than 30, but try it in the command area and see what happens. Mark Guzdial

I've been able to follow everything in class. I know how to do things, but I guess we haven't really learned why things work and how they are working. That's why I'm having trouble with the pre-quiz.

I read your answer to the question above about the color compontent of a pixel being 1.5. Then I tried reading the specific pages in the book (which didn't really help answer if for me) and I tried creating and running replaceLightBlue on a couple of different pictures from Mediafiles. However, I can't really determine what happened to the same type pixels in that picture, because I can't open up a file in Squeak to find the original color of certain pixels and thus find one that is close to what I need as an exmaple (and any change that occured was too small to be noticable). Please help!!

Look at the slides in http://coweb.cc.gatech.edu:8888/uploads/cs1315/24/LoopsForPictures.6.ppt. I explain how to use the commands like getPixel and getColor to CHECK if pixels change and by how much. It is hard to see what the changes are. That's why you need to look at individual pixels. Have you tried the Help in JES for figuring out how to use the Squeak MediaTools? Mark Guzdial

I know you can't have 1.5 as the color component of a pixel and that it has to be an integer. My question is, what integer do you use? Do you round up and have 2 or just use 1 since it's 1.5?

See the below suggestion: Try it. Mark Guzdial

In the prequiz, same distance line, do we add 30 to 128 or subract 30 from 128 to figure out which pixel coordinates we change the red within.

Neither – you use the distance formula. Mark Guzdial

Everyone I have talked to has done the same thing I have done and has the same question about the 1.5 pixel. I have tried reading the book and I have looked at the suggested notes and I have tried running the program and looking at the pixels. I can't get it to work and I can't find an answer to the question. What are we missing?

i have come to class every day and understood what was going on, but i cannot answer any of the midterm review questions....

If you didn't do all of the examples, you may not have actually understood it. Take a look at What to do if you don't understand a program? Do you understand every example we've done such that you know what every variable's value is at any point? That's what's needed to really understand the programs. Mark Guzdial

Note:

I'm quite happy to help you through the midterm exam review. Start asking your questions about the problems, your guesses as to the solutions. Let's work it out. Mark Guzdial

I have been looking for the pixels with the color "coordinates" that are within 30 of the light blue color specified and then Ihave been changing those red values but then you get the 1.5 component. I cannot think of another way to do this problem. I have looked everywhere! Help!!!!

SAME PROBLEMS HERE! And I havent been able to talk to ANYONE who knows what is going on. It seems like the actual quizes and exams are going to be impossible - the labs and HWs are doable... but I am lost.

Has anybody tried it? Make a picture, then p = getPixel(picture,1,1) setRed(p,1.5) print getRed(p). What does it say? That's your answer. Mark Guzdial

All I keep getting is the value 1 when I do the above suggestion, what am I doing wrong?

Nothing! You did it absolutely right! So what does that tell you what happens when you try to set the red to 1.5? Sounds like you get 1, not 2. Mark Guzdial

Oh, so I was testing whether it would use 1 0r 2 when given the value 1.5?

Uh-huh!

okay, if I did this thing correctly, then I would say that this problem has a sort of "trick question" mentality. I mean, if I did it right, then that means that all of the values in the top row remained the same, and that only the first two columns in the second row changed. Did anybody get the same kind of result? Am I totally off base?

i got the same result- i think it's right

awesome, anyone else get similar results?

I got the same thing too

I got that the middle value on the top row changes along with the first two columns in the second row. Should change since it is just (1,0,128)

nevermind

on the lab- question #6- why does it give the formula with the inputs for column I and then say at the end to use column G? i know someone brought it up in class about getting very different values, now im having the same problem...

We are calculating the variance in two different ways. We do all the calculations ourself using column I, but when we use Excel's VAR formula, it does all that calculating for us Adam Wilson

has anyone done problem 10 yet? i am getting the first value, but then i am getting a neg. number for the second which is impossible. also, the equation that the lab gives us for problem 10 says 19 but shouldn't it be 20 because 19 is included in the first set? then the next one would be 30 right? PLEASE HELP!!!!!!!!!!!!!!!!

Make sure that you only include what you mean to include in your calculations. When something is in the range 20-29, it is less than 30, but greater than 20. You need to take that into account in your formulas. Adam Wilson

That is the same question I have. I also don't understand what 11 is asking us. Where do we put the ranges and data sets?

You're just finding the min and max of weights in each fuel bracket. The main point is to include the error bars on your graph, so put your median calculations somewhere out of the way. Maybe around where you did your other on-the-side calculations Adam Wilson

For problem 3 of the lab, when you say "We know that MPG is in column D" you really mean the cyllinder values right? Because that's what we're supposed to be calculating??

Sorry, typo

For the graph my excel says it has a limit of 255 pieces of data it can include it there anything i can do to change that?

For problem 8 am I supposed to have the bar graph we made for the weights also. Becuase it won't let me make a graph with more than 255 points in it. What should I do about this?

You can delete the graph you made right before problem 8. The histogram (problem 9) isn't for more than 255 pieces of data.. - Error: this should not happen

I have suddenly experienced a problem with turnin on my assignment. All of my previous assignments have been turned in successfully. I have no idea why this has happened. Can anyone help? I keep getting an error message when trying to turnin and have already checked my settings.

For question 3 in the Lab, do you want MPG or do you want what's in column D? Someone else asked the question earlier, but the answer given was still somewhat unclear.

Column D = Cylinders, and yes we want the info on cylinders, not MPG for problem 3 - Error: this should not happen

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Comment Areas-Spring 2003 last edited on 30 January 2006 at 6:41 am by r80h18.res.gatech.edu