Question

Matlab help

Answer 1

%% 5.18
% According to Moore's law (an observation made in 1965 bt Gordab
% Moore, a cofounder of Intel Corporation), the number of transistors
% that would fit per square inch on a semiconductor integrated circuit
% doubles approxmiately every 2 years. Although Moore's law is often
% reported as predicting doubling every 18 months, this is incorrect.
% A colleague of Moore took into that the fact that transistors
% performance is also improving, and when combined with the increased
% number number of transistors results in doubling of performance every
% 18 months. The year 2005 was the 40th anniversary of the law.
% Over the last 40 years, Moore's projection has been consistently met.
% In 1965, the state-of-the-art technology allowed for
% 30 transistors per square inch. Moore's law says that the
% transistor density can be predicted by d(t) = 30(2^t/2), where
% t is measured in years.

% (a) Lettting t = 0 represent the year 1965 and t = 46 represent 2011,
% use this model to calculate the predicted number of transisitors per
% square inch for the 46 years from 1965 to 2011. Let t increase in
% increments of 2 years. Display the results in a table with two
% columns - one for the year and one for the number of transistor.

t = 0:2:46; % time measured in years, from 1965 to 2011
d(t) = 30*(2.^(t ./ 2)); % transistor density function
table = [t', [d(t)]'];



% (b) Using the subplot feaure, plot the data in a linear x-y plot, a
% semilog x plot, a semilog y plot, and a log-log plot. Be sure to
% title the plots and label the axes.
@jim_thompson5910

Answer 2

Okay so for some reason I can't get d(t) output.

Answer 3

to output*

Answer 4

the notation ` d(t) ` won't work. Let me think of how to fix that

Answer 5

I could just call it 'd' right?

Answer 6

yes you would say

d = 30*(2.^(t ./ 2))

Answer 7

`table = [t', [d(t)]']`
should be
`table = [t', d']`

Answer 8

okay let me try that, sorry for the late reply I was doing something and almost forgot I was on opensudy

Answer 9

nice, it worked. Thanks!

Answer 10

so any suggestions for part b?

Answer 11

`Using the subplot feaure, plot the data in a linear x-y plot, a `
` % semilog x plot, a semilog y plot, and a log-log plot.`

so you'll have 4 separate plots

* linear x-y plot
* semilog x plot
* semilog y plot
* log-log plot

Answer 12

okay so linear, semilog, and log-log are commands?

Answer 13

let me do a bit of research

Answer 14

so a linear x-y plot is a normal plot you're familiar with

http://www.mathworks.com/help/matlab/ref/plot.html

where the x and y scale are incrementing by the same amount each time

Answer 15

I will figure it out.

Answer 16

http://www.mathworks.com/help/matlab/ref/semilogx.html

makes the x scale a log scale

instead of incrementing by the same amount, the scale looks like this

https://upload.wikimedia.org/wikipedia/commons/8/83/LogLogPlot_of_Line.GIF

notice how the x axis is going by 10^1, 10^2, 10^3, etc. It's not incrementing by the same amount each time. Instead, it's showing powers of 10

Answer 17

http://www.mathworks.com/help/matlab/ref/semilogy.html

does the same thing, but this time to the y scale. The x scale is linear

and finally

http://www.mathworks.com/help/matlab/ref/loglog.html

will make a log-log plot

Answer 18

a log-log plot is where both axis (x and y) are on a log scale

Answer 19

@jim_thompson5910 okay so I used the plot(x, y) it's not linear. it's exponential.

Answer 20

y values increase by a lot for every increase in x

Answer 21

plot(x,y) isn't referring to the shape of the curve you see

it's referring to how the scales are set up

if you increment by 10 each time, then the scale is a linear scale

Answer 22

you could have a nonlinear curve (eg: exponential curve) on a linear scale xy axis

Answer 23

okay that makes sense. I just wanted to double check to make sure my logic is correct.

Answer 24

hmm I wonder if there is a way to increase the values on x and y. What I mean is increase the size of the interval so the graph looks linear.

Answer 25

I think it's possible. If you adjust the scales, then it warps the shape. I think some cases you can turn a curve into a straight line (when going from normal linear scale to log scale)

Answer 26

I would have to increase my t value though. The end of your last comment how would you do that?

(when going from normal linear scale to log scale)

Answer 27

one moment

Answer 28

okay I am working on the semilog x plot

Answer 29

% linear x-y plot
subplot(2, 2, 1);
y1 = log(t);
semilog(t, y1);

title('Linear x-y plot');
xlabel('X'); ylabel('Y');

http://www.mathworks.com/help/matlab/ref/semilogx.html

Answer 30

^^ that will give me a linear line if I use y1 = log(t) and semilogx(t, y1)

Answer 31

let me try it out

Answer 32

yes I'm getting a straight line as well

Answer 33

Would that be an appropriate answer to the first part of part (b)?

Answer 34

yes I think so. They just want to see the 4 plots

Answer 35

Okay awesome

Answer 36

is the semilog y plot going to look linear as well?

Answer 37

not for log(x) but it does for exp(x)

Answer 38

okay give me a sec I think I know what you are talking about

Answer 39

% linear x-y plot
subplot(2, 2, 1); % subplot one
y1 = log(t); % log function used to create linear line
semilogx(t, y1); % semilog function
title('Semilog x plot'); % title for subplot one
xlabel('X'); ylabel('Y'); % x and y axis lables

% semilog x plot
subplot(2, 2, 2);
semilogx(t, d);
title('Semilog y plot');
xlabel('X'); ylabel('Y');

Answer 40

let me make my last subplot and I will paste my whole entire code here.

Answer 41

% (a) Lettting t = 0 represent the year 1965 and t = 46 represent 2011,
% use this model to calculate the predicted number of transisitors per
% square inch for the 46 years from 1965 to 2011. Let t increase in
% increments of 2 years. Display the results in a table with two
% columns - one for the year and one for the number of transistor.

t = 0:2:46; % time measured in years, from 1965 to 2011
d = 30*(2.^(t ./ 2)); % transistor density function
table = [t', d']; % table with year and number of transitors

% (b) Using the subplot feaure, plot the data in a linear x-y plot, a
% semilog x plot, a semilog y plot, and a log-log plot. Be sure to
% title the plots and label the axes.

% linear x-y plot
subplot(2, 2, 1); % subplot one
y1 = log(t); % log function used to create linear line
semilogx(t, y1); % semilog function
title('Semilog x plot'); % title for subplot one
xlabel('X'); ylabel('Y'); % x and y axis lables

% semilog x plot
subplot(2, 2, 2);
semilogx(t, d);
title('Semilog x plot');
xlabel('X'); ylabel('Y');

% semilog y plot
subplot(2, 2, 3);
semilogy(t, d);
title('Semilog y plot');
xlabel('X'); ylabel('Y');

% log-log plot
subplot(2, 2, 4);
loglog(t, d);
title('Log-log plot');
xlabel('X'); ylabel('Y');

Answer 42

shouldn't `plot(t,y1)` be in there somewhere? towards the top of part b?

Answer 43

I see what you are saying. The code that creates the linear x-y plot doesn't need plot(t, y1)

Answer 44

% linear x-y plot
subplot(2, 2, 1); % subplot one
y1 = log(t); % log function used to create linear line
semilogx(t, y1); % semilog function
title('Semilog x plot'); % title for subplot one
xlabel('X'); ylabel('Y'); % x and y axis lables

Answer 45

subplot(2, 2, 1);

looks like it sets up an empty plot to fill it with something, but you forgot about the actual plot command for the linear x scale and linear y scale

Answer 46

% linear x-y plot
subplot(2, 2, 1); % subplot one
y1 = log(t); % log function used to create linear line
semilogx(t, y1); % semilog function f
plot(t, y1);
title('Semilog x plot'); % title for subplot one
xlabel('X'); ylabel('Y'); % x and y axis lables

% semilog x plot
subplot(2, 2, 2);
semilogx(t, d);
title('Semilog x plot');
xlabel('X'); ylabel('Y');

% semilog y plot
subplot(2, 2, 3);
semilogy(t, d);
title('Semilog y plot');
xlabel('X'); ylabel('Y');

% log-log plot
subplot(2, 2, 4);
loglog(t, d);
title('Log-log plot');
xlabel('X'); ylabel('Y');

okay how about now?

Answer 47

That doesn't give me a linear line though.

Answer 48

concave down graph

Answer 49

for some reason you have semilogx twice

Answer 50

I'd delete the first semilog to make plot come first

Answer 51

% linear x-y plot
subplot(2, 2, 1); % subplot one
plot(t, y1); % semilog function f
title('Linear x-y plot'); % title for subplot one
xlabel('X'); ylabel('Y'); % x and y axis lables

% semilog x plot
subplot(2, 2, 2);
semilogx(t, d);
title('Semilog x plot');
xlabel('X'); ylabel('Y');

% semilog y plot
subplot(2, 2, 3);
semilogy(t, d);
title('Semilog y plot');
xlabel('X'); ylabel('Y');

% log-log plot
subplot(2, 2, 4);
loglog(t, d);
title('Log-log plot');
xlabel('X'); ylabel('Y');

Answer 52

when I use plot(t, y1) though it's still concave down graph, not linear

Answer 53

much better

and it should be curved. On a linear scale, log(x) looks like you would see in a previous algebra class. A curved line that is concave down

Answer 54

is it curve because we have large y values for every 1 increase in x?

Answer 55

I didn't use log(x) in subplot1

Answer 56

wait, I'm curious why you have

y1 = log(t)

for the plot but you use d for the other graphs

Answer 57

shouldn't it be `plot(t, d)` ?

Answer 58

yes it should be. That looks much better

Answer 59

i have another quick question. let me make a new thread