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# Johannes Fischer

Last seen: 約1ヶ月 前 2017 年からアクティブ

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Creating a custom colormap with a specific range of colors
I'm not sure I understand your problem correct, but does % create matrix with vals -50 50 matrix = 100 * (rand(100, 100) - 0.5...

2年以上 前 | 0

Find same numbers in two vectors
I think what you need is the ismember function: a = [3,8,10,11] b = [2,3,10,12] result = a(ismember(a, b)) % or result = ...

2年以上 前 | 0

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How to find a Y value of a given X?
You want to use an anonymous function. So in your case: % define the anonymous function v = @(t) 50*exp(-1600*t) - 50*exp(-40...

3年以上 前 | 0

Find different possible combinations of the rows of two matrices.
a = [1 2 3; 4 5 6; 7 8 10]; % 3 by 3 matrix b=a + 10; % 3 by 3 matrix r=size(a, 1); % create repetitions of values a = re...

3年以上 前 | 0

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Shepp-Logan phantom dataset
In their paper from 1974, they call these ellipses tumors (see caption of Figure 1) https://web.archive.org/web/20160304035526/...

3年以上 前 | 1

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Repeating a process with changing file names, possibly with a loop.
Assuming you dont need a001 etc. % N is the number of matrices for ii = 1:N % load or create A %... a...

3年以上 前 | 0

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Change pixel color and intensity independently in an image
Here is how i would try to do it: % First, you need to get the image that you see as an RGB-matrix. If your % ratioImage is an...

3年以上 前 | 0

How to repeat number of array by values in another matrix
array = [3 4 2 1]; matrix = [0 2 4 5; 1 3 2 6; 1 0 3 5; 5 6 3 1]; % first, you need a vector with the same length of array t...

3年以上 前 | 1

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How can I check that a newly generated sequence is already in the existing structure list or not?
newPerm = [2 1 3 4]; % this line basically runs over the elements of your struct array and checks whether the array in field ...

3年以上 前 | 0

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Creating 3D surface from binary slice images
Have a look at isosurface

Using an index in a loop as a variable in another function
You need to provide it as an additional argument (the same holds for d, g, and h): ... alpha(n+1,j) = alpha(n,j) + h * vel...

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Array indices must be positive integers or logical values.
The first entry in any kind of Matlab vector/array/matrix... is indexed with 1 (and not 0, as for example in C++). That is why y...

4年以上 前 | 0

Save elements of an array in a byte variable.
% random array of 8 rows with 4 bytes each bin = logical(round(rand(8, 32))); % how many bytes are there in total NoBytes =...

4年以上 前 | 2

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Selecting specific values from an array based on a defined condition
Th logical expression 0 <= m+d <= 300 is not interpreted by Matlab as you think it is. It rather is interpreted as (0 <= m+d...

4年以上 前 | 1

How to express coordinate range of an area
You are looking for the colon operator (https://www.mathworks.com/help/matlab/ref/colon.html) x = 1119:1121; y = 392:394;

4年以上 前 | 0

How to make the binarized image clearer
The problem why your output looks like this is not necessarily to do with the imbinarize function. The problem lies in the way t...

4年以上 前 | 0

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Returning negetive numbesr from text file using regexp
With questions like these it's very helpful to have an example of waht exactly your data looks like. If you know exactly how you...

4年以上 前 | 0

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Swapping the columns based on matrix even length
Assuming that there is always an even number of columns: matrix = repmat(1:10, [3, 1]); L = size(matrix, 2); ind = [2:2:L...

4年以上 前 | 0

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How to fuse SPECT and CT images having different matrix sizes?
You can import the data using dicomreadVolume (https://www.mathworks.com/help/images/ref/dicomreadvolume.html) There is an intr...

4年以上 前 | 1

How can I fit a Gaussian to data that only forms the peak
You should always help your fitting algorithm by setting upper and lower bounds for the parameters. Even more important are star...

4年以上 前 | 2

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ranking of vector with non-unique elements
So you want to order starting with the highest value? F = [10.1 31.0 20.5 20.5 10.1] [~, ~, rankF] = unique(max(F)-F)

4年以上 前 | 3

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Standard Deviation of 3D matrix with NaN elements
As described in the doumentation for std, there is a flag on how to deal with 'NaN' values. If you want the standard deviation o...

4年以上 前 | 1

How to make two numeric field related in GUI?
The 'Callback' property of the uicontrol defines which function to call when you press enter while the edit field is in focus. A...

4年以上 前 | 0

How to randomize audio files
What kind of randomization do you want? Play all sounds once, before playing a sound twice? randomizedOrder = randperm(80); ...

4年以上 前 | 0

How to reshape a square matrix diagonally to a vector?
I would start with writing down the subscripts in the order you want to select the elements of the matrix. A=[0 1 0; 1 1 1...

4年以上 前 | 1

How to assign a different name of a matrix for each iteration?
You could use assignin for that purpose: for j = 1 : size(varargout,2) fn = modalfit(varargout{1,j}, f, fs, 10, 'FreqRange', ...

4年以上 前 | 0

for loop values of certain output range
Two possible solutions: x = 3; idx = 1; for c = -2:1:2; for q = -2:1:2; g = (c*x)+q*(c+x); % g at this...

4年以上 前 | 0

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How to save the image WITHOUT the white background using imwrite (advanced problem)
% read image as NxMx3 rgb matrix RGB = imread('bird1.png'); imshow(RGB) s = size(RGB); rectangle('position',[1 1 s(2) s(1)...

4年以上 前 | 0

How do I check if a folder exists which has a variable name?
Your code is trying to store in fname the content of the field 'bin' of the struct 'Measurement_20190829_18_15_10', which propab...

4年以上 前 | 0

How to find the previous position in an array where a value is met?
This is an ideal playgrouond to see how you can increase speed by avoiding for loops. % My idea is to create an array, that in ...

4年以上 前 | 2

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