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# Johannes Fischer

##### Last seen: ein Tag ago
70 total contributions since 2017

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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...

4 Tage ago | 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...

13 Tage ago | 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 Monate ago | 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 Monate ago | 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 Monate ago | 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 Monate ago | 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 Monate ago | 0

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

9 Monate ago | 1

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...

10 Monate ago | 0

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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...

11 Monate ago | 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 =...

12 Monate ago | 1

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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...

12 Monate ago | 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;

12 Monate ago | 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...

etwa ein Jahr ago | 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...

etwa ein Jahr ago | 0

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Solved

Vector creation
Create a vector using square brackets going from 1 to the given value x in steps on 1. Hint: use increment.

etwa ein Jahr ago

Solved

Doubling elements in a vector
Given the vector A, return B in which all numbers in A are doubling. So for: A = [ 1 5 8 ] then B = [ 1 1 5 ...

etwa ein Jahr ago

Solved

Create a vector
Create a vector from 0 to n by intervals of 2.

etwa ein Jahr ago

Solved

Inner product of two vectors
Find the inner product of two vectors.

etwa ein Jahr ago

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...

etwa ein Jahr ago | 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...

etwa ein Jahr ago | 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...

etwa ein Jahr ago | 0

| accepted

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)

etwa ein Jahr ago | 3

| accepted

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...

etwa ein Jahr ago | 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...

etwa ein Jahr ago | 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); ...

etwa ein Jahr ago | 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...

etwa ein Jahr ago | 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', ...

etwa ein Jahr ago | 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...

etwa ein Jahr ago | 0

| accepted

Solved

Alternating sum
Given vector x, calculate the alternating sum y = x(1) - x(2) + x(3) - x(4) + ...

etwa ein Jahr ago