# Joseph Cheng

Systems Engineer for Electro-Optical Systems

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**Content Feed**

How do I pass coefficients to function handle as an array or list?

i think you just answered yourself in your question y = @(y0,a,b,NN) y0 + a*x(NN) + b*x(NN).^2; %simulate parabolic data yDIF...

4 months ago | 0

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Issue in plotting binary image boundaries with real axis values

so you'll need to find the conversion between pixel to linear xy (mm). sort of the mm/px scale factor + offset to 0; from th...

4 months ago | 0

how can i automatically crop this image? if it is possible.

well, you can find the corner squares by doing the following: img = (imread('https://www.mathworks.com/matlabcentral/answers/up...

4 months ago | 0

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Create variable with name from other variable string

While it is not adviseable to have variables created in this way maybe you have a good reason to but still un-adviseable but her...

4 months ago | 1

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How to find end of time series in plot

to go with your example of pos where pos = [0.11, 0.12, 0.12, 0.12, 0.12 0.12, 0.14, 0.14, 0.11, 0.16, 0.13, 0.13, 0.13, 0.13]...

4 months ago | 0

remove empty rows of a cell

you can use the function cellfun() in conjunction with isempty: clear K %generate dummy K for Cind = 1:2 for Rind = 1:4 ...

4 months ago | 0

Issues in For loop

if we break down your for loop: for i=1:38976; %this if statement will be done if j==120 %an okay statement here b...

4 months ago | 1

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How to find the two minimum values ?

well to remedy this you shouldn't "delete" the entry of the min point but stick in a large value or Nan and use nanmin(). by de...

4 months ago | 0

3d to 2d matrix

take a look at the function squeeze() for ind = 1:3 val(1,1,ind)=-ind; end disp(val) u2 = squeeze(val); disp(u2)

4 months ago | 1

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How to get data points within current camera view?

So... if i'm not mistaken pan in matlab moves the axes limits of the plot and not panning/translating the camera, similarly zoom...

4 months ago | 0

Looking for a way faster than find?

without doing some testing to actually test if its faster you can use the found 1's in a to only select a list of indexes A = ...

4 months ago | 0

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Incorrect datatip location on interpolated data

so you can see what is happening if you plot it as just markers in this animated example: figure; hold on; hPlot = plot(1:10, ...

4 months ago | 0

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Taking average of pixel values across multiple frames

couldn't you just put it into a non cell matrix of 5504 x8256 x 3 then use mean(data,3) to take the mean in the 3rd dimension? o...

4 months ago | 1

Why am I getting an invalid file identifier error when using "parfor" but the same function works fine (albeit slow) with "for"?

From the looks of it you've opened a file then trying to use parfor to grab items out of the opened file. However thats where t...

4 months ago | 0

How to get rid of blank space in a heatmap panel of 3 figures?

have you looked at the functions axis equal or axis square those might be applicable to you and not have to only use top h...

4 months ago | 0

How read in comment style to skip the header of a text file?

you can quickly scan the file(s) for the number of header lines like file= 'Graphite_Node_test.txt'; fid = fopen('Graphite_Nod...

4 months ago | 0

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Contour is plotting my data in reflected order?

From a quick test you might not be asigning the x and y values when performing your contour() function. by doing so matlab will...

4 months ago | 0

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Create a matrix with elements clockwise

While probably not the most efficient way you can fill in edges like i've done here: clc;clear all x = zeros(5,8); %generate m...

4 months ago | 1

Update a for loop with if statements

Without running your code i think you can create a sign variable of (-1)^(0 or 1) which switches between 0 or 1 depending on whe...

4 months ago | 0

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Represent array in percentage

you would take your array, subtract the minimum, then divide by the resulting maximum x 100 x = [2.4:.4:4.2]; x = x-min(x); ...

4 months ago | 1

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How to make the length/dimension of 6 different 3D vectors the same?

probably the easiest way is to fill a zero array created to be the same max size then populate the indexes with the values: var...

5 months ago | 1

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Extract pixel values inside a Binary Mask

since you already created a binary mask you can just index multiply " .* " the mask with the original image as outside is 0 and...

5 months ago | 0

how to color and label only certain histogram bars?

Here is an example for @Adam Danz said with using bar y = randn(100); [N X]=hist(y(:),10); %plot all the data figure,clf,hb...

5 months ago | 1

Looking for a matlab script that extracts data from a plot figure ( here 2D contours from Covariance matrix or Markov chains) and reproduce the original figure

your graph is a bit messy with text and lines that denote items. here is a quick example that may push you along. It'll need a...

5 months ago | 0

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Scientific notation at y-axis with yticks/yticklabels

from the looks of it the desired state is also plotting in a log10. you can change the current axis by set(gca,'yscale','log'...

5 months ago | 0

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Find the indices of the imaginary element of the matrix

you can do a comparison to the real(A) like A=[1 2 3; 4+i 5 6-i; 7 8+i 9] [row col]=find(A~=real(A)) ...

5 months ago | 0

How to make the code efficient?

You can do things all at once cine you're not dependent on previous values. n=4 x=[0:n-1]; y=[0:n-1]; k = 0; %%Orig_code ...

5 months ago | 0

Double sigma with exception case

in your nested forloop you can put a check in for if j==i then continue. you do have a check up there with i~=j which should w...

5 months ago | 0

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Remove shadow and unwanted background

to get your started you can see that the tissue and the shadow area have similar values in all the color channels. you can do a...

5 months ago | 0