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# Johannes Fischer

Last seen: Today Active since 2017

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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...

9 months ago | 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 = ...

1 year ago | 0

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Solved

Sum of first n terms of a harmonic progression
Given inputs a, d and n, return the sum of the first n terms of the harmonic progression a, a/(1+d), a/(1+2d), a/(1+3d),....

1 year ago

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...

2 years 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...

2 years 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/...

2 years 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...

2 years 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...

2 years 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...

2 years 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 ...

2 years ago | 0

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

2 years 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...

2 years 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...

2 years 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 =...

2 years 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...

3 years 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;

3 years 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...

3 years 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...

3 years 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.

3 years 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 ...

3 years ago

Solved

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

3 years ago

Solved

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

3 years 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...

3 years 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...

3 years 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...

3 years ago | 0

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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)

3 years ago | 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...

3 years 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...

3 years ago | 0