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# Joseph Cheng

##### Last seen: 2 days ago
609 total contributions since 2014

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Radiation Heat Transfer — View Factors (1)
View factors (aka configuration factors) are utilized in some radiation heat transfer models to estimate heat transfer rates bet...

3 months ago

i got index exceeds matrix dimensions.??
You should put a breakpoint at that line and then check the dimensions of the curs variable. without running your code and with...

1 year ago | 0

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Replotting Data vs. Storing Plots/Images
I think the answer would be dependent on how many points are in each line and the size of the images you're going to be pulling ...

2 years ago | 0

How to create a checkerboard matrix without inbuilt function.
There are much easier ways to do this than nested for loops, reshape is readily available. if you *must* do it with for loops y...

2 years ago | 0

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does someone know if it's possible to have popupmenu in inputdlg?
Absolutely you can, however its not as straight forward as inputdlg() or questdlg(). you'll want to look at the example here: ...

2 years ago | 0

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How can I change the LSBs of consecutive elements of an array?
you could use bitand() a = [23, 255, 67, 89, 45, 90, 34, 12]'; n=3; b = bitand(a ,255-n,'uint8') disp(dec2bin(a)) di...

2 years ago | 0

import multiple spreadsheats at once (.xlsx files)
well first you'll want to get away from generating variables in that fashion as you'll basically have A400 or more which is hard...

2 years ago | 0

Looking for a word in a 2D array
I would take a look at the function strfind(), and lower() or upper(). strfind() will return the starting index value of the ...

2 years ago | 0

Project 3D points to a surface
you could try something like this. my curve and fit method is probably different however what you can do is use find() to deter...

2 years ago | 1

Can I match data from several find functions?
what you should do is get rid of the find() for each parameter filter. keep it as a logical and then you can directly use the l...

2 years ago | 0

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How to average plots that differ in x and y data?
you can do something like x1 = 0:.01:4; x2 = 0:.03:5; x3 = 0:.02:6; y1 = sin(3*pi*x1); y2 = sin(3*pi*x...

2 years ago | 0

How to get the central data of a matrix?
you'd use the parameter 'same' in the convolution function x = [0 1 2 3 4 5 4 3 2 1 0] conv(x,[0 1 0],'same') otherwise ...

2 years ago | 0

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Change axes limits interactively
you can try something like this, which really depends on how you want the user to input the different limits function uiexa...

2 years ago | 1

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error using randi: size inputs must be scalar
you actually want to do for n=1:4 a{n}= randi(10,n)-1; b{n}= randi(10,n)-1; fprintf('n = %d:\n', n)...

3 years ago | 0

How can I plot mean +/- 1 standard deviation for every data point in my dataset ?
have you looked up the function errorbar()? it should get you what you'll need

3 years ago | 0

searching through RNA sequence for a string of characters
so, do you store the full compliment data in an array such that you can %gen dummy data comp = 'AGCT'; list = comp(ran...

3 years ago | 0

Outputting gyroscope data to array
you're overwriting it with the p(n) as n only goes from 1 to 10 again and again. you'll have to increment p(#) beyond n or mult...

3 years ago | 0

how to plot normalized column vs another colomn
must be missing something as you have it right there plot("your other column",i./max(i),'.') then you'd fit a line and e...

3 years ago | 0

How do I create an animation with a coloured sphere changing in time? (for climate modelling)
you can do something like this [x,y,z] = sphere(30); [sx sy]=meshgrid(-1:.01:1,-1:.01:1); I=3*sin(2*pi*2*sx)+cos(2*pi...

3 years ago | 0

How to upload an image to a GUI frame?
so i take it you have an axes frame that you've tagged as imagedisplay. i'm curious why with said function you don't get warnin...

3 years ago | 0

Repeating If statement after variable change
not sure what you mean by repeat first with SS(1)==# as it wouldn't do the first if statement but the lower elseif statement. i...

3 years ago | 0

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How do I piece together a 2-dim image using 3 given images, each representing R, G, B?
you should be using cat(3,red,green,blue) because you want to stack in the 3rd dimension. x = randi(3,3,3) x = ...

3 years ago | 0

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Legend for a graph displaying multiple runs
you can look into specifying which points/lines are plotted in the legend() help documentation. I made a quick example that y...

3 years ago | 1

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I need to create a 3 by 3 window and calculate mean within the window. This window is to move through the image. How can I do it?
I would take a look at the conv() and conv2() function. you would use something like [1 1 1;1 1 1;1 1 1]/9 to get mean. and the...

3 years ago | 0

How to make a 2D graph from text file
I can point out a few things. # if you look at M isn't that what you're trying to plot with A? as it should include both c...

3 years ago | 0

how to replace values of a matrix, if another matrix meet certain conditions?
i may be over simplifying it but doesn't the greater than (>) inequality just do it? A=magic(5) B=A>18

3 years ago | 1

Pulse train with duty cycle variable.
why not try something like this: t=0:per/1000:per-per/1000; %define period normal = zeros(1,numel(t)); normal(t<per*dut...

3 years ago | 0

Is there a way to remove the nested for loops from this segment of code? I'm trying to make the code generic so it can take in n-number of moment arrays.
to make it more generic you could do something like momentind = [1 1 1 1 1 1] cind = 1; while momentind(end)~=3;...

3 years ago | 0