Matlab-Intro-MIT-IAP-2008 Google Group

Class is now over.

2008-01-31T20:18:53Z

Hi all,

I'm a little disappointed by the weak show of people today...The
project is the part where you would have learned the most in this
class. By not doing the project, you are committing yourself to
forgetting most of the material. You need to strike the metal while it
is hot...But there's still hope! Finish your project over the weekend

Feedback on Intro to Matlab 2008 (Yossi Farjoun)

2008-01-30T18:11:17Z

Hi all.

In order to create a better departmental offering, and to get feedback
on my teaching, I ask that you take a few minutes to answer the
following questions. In order to guarantee you express your true
thoughts about me and the class please email your reply to
w...@math.mit.edu (the undergraduate office). Make sure you do not

Re: Question about today's exercise

2008-01-25T13:00:29Z

Masaharu,
The third way you suggested is one way I was thinking about (note that you
can change the 5 to a 100 and it will create a 100x100 matrix...)
but you can also do
a=[1:5]'
r=a(:,ones(1,5))
The fourth way you did has a colon between two vectors...I'm not sure what
you expect that to do.
cheers,

Re: Question about today's exercise

2008-01-25T19:56:40Z

Thanks for your reply.
is a quite interesting way. This trick looks a bit similar to ' for i
= [ ones(1,5) ] ' in respect that a kind of iterator is proceeding
from 1 to anther 1, right ? Now I understood how it is going in Matlab.
Have a good trip.
Masaharu

View this page "Lecture 6 Notes"

2008-01-24T19:20:27Z

Lecture 6 notes are published in case you wanted them...:-)

Click on [link]
- or copy & paste it into your browser's address bar if that doesn't
work.

Lecture 6 write-up

2008-01-24T14:41:26Z

Hi all.

I'm leaving for the weekend right after class today, and thus will not
have the time to write up my lecture summary.

I would greatly appreciate if a few of you could collaborate on
writing up the notes.

You can simply click on "Pages", and then on "new page", and type
away. you can edit a previously edited page (kind-of like a wiki), or

Re: counter

2008-01-24T04:45:12Z

Nice code.

2 comments.

1. You have an empty line as the first line of the code. the very
first line must have the "function y = ...." code, or a comment
(starting with %)
no empty lines allowed before the keyword function...This might be
your only problem.
2. you can put the y=counter1-1 outside the while loop. no need to

counter

2008-01-24T04:42:18Z

Hi Yossi,
I have attached my version of the last-ish problem for lecture 5. I can't
seem to get it to work. What would you suggest?
function y = counter(x)
counter1=1;
while x>1
counter1=counter1 + 1;
if mod(x,2)==0
x=x/2;
else
x=3*x+1;
end

Re: Lect 5 exercise -20000th Fibonacci number

2008-01-24T03:15:16Z

GOOD POINT!

I wasn't thinking when I gave you that exercise...it does indeed grow
to be too big for matlab. So let's find the 100th Fibbonacci number
instead...(I'll change the exercise)

Yossi.

Lect 5 exercise -20000th Fibonacci number

2008-01-24T03:12:35Z

Hi Yossi,
I was doing the exercise, and it seems to be working, except the value for
the 20,000th number comes out as Inf. I tried changing the format of the
number, but it didn't help. Is there a way to see the value of the number
or is it just Inf?
Thanks,
Jessica

Re: help: lecture 4 question 2

2008-01-23T20:16:42Z

Dear M,

There are several things that need to be corrected in your code:

1. (line 2) 1:10^(-6) is an empty vector. be careful with operator
precedence.
2. (line 3) even if that was a vector, it would only be a vector of
size 10...and in the loop, n would just be a single number...not what
you wanted I think. Perhaps you need another variable...just like my

help: lecture 4 question 2

2008-01-23T20:05:27Z

Hello,
I have problems solving the second questions on lecture 4, warm up:
Find a value of N so that the sum is close to pi/4 (with difference < 10^-6)
I have written the following code:
counter=0;
for n=1:10^(-6)
a=(1).^(n+1)./(2.*n-1);
sum(a);
counter;
if
sun(a)-(pi/4)<10^(-6);
break

Re: sprintf lec4

2008-01-23T20:01:04Z

Shammi,

great questions.

s is a "format string" when used as the first argument of fprintf or
sprintf it tells the function how to generate the result (sprintf
returns the result, while fprintf write the result to the screen, or a
file)

in the format string, you can have "place holders" for other input. so

sprintf lec4

2008-01-23T06:13:18Z

I was running this if loop from your lecture notes

x = rand;

s = 'The number %g is %s than 0.5\n';

if x<0.5

fprintf(s,x,'less')

else

fprintf(s,x,'more')

end

questions: what does the %g and %s represent? what does it say in
english? also are the alphabets random or each signify a different

Re: syntax on summing

2008-01-22T19:49:36Z

Hello,

I may have already answered you in class, but in any case, I'll answer
the list. The division needs to be pointwise. so use ./ instead of /

cheers,

Yossi.