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# Muhamed Sewidan

##### Last seen: 5 dagar ago
61 total contributions since 2019

Hi, my name is Muhamed a physicist who is interested in puzzles whether they are embedded in the nature around us or in coding.

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Crop an Image
A grayscale image is represented as a matrix in MATLAB. Each matrix element represents a pixel in the image. An element value re...

5 dagar ago

Question

My code takes so long to execute
My code works fine until it gets to this block. This loop takes too long to execute. Is there any way to solve this problem? if...

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Question

How to fit two separate variables with smoothing spline, Gauusian or polynomial?
I have these two variables and want to fit and plot them. lam = [0.30,0.31,0.32,0.33,0.34,0.35,0.36,0.38,0.39,0.41,0.43,0.45,0....

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Question

How to make the frequency vector to analyze a complex signal?
I have this example and I'm puzzled with the frequency vector (hz) if I change any parameter in it, the result won't be the freq...

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Question

In "Analyzing Cyclical Data with FFT" example, how the frequency was calculated?
and how it can be calculated for other examples? is there a general equation or formula to calculate it?

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Calculate area of sector
A=function(r,seta) r is radius of sector, seta is angle of sector, and A is its area. Area of sector A is defined as 0.5*(r^2...

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Pizza!
Given a circular pizza with radius _z_ and thickness _a_, return the pizza's volume. [ _z_ is first input argument.] Non-scor...

Question

Should I use the absolute value of fast Fourier transform or the conjugate in signal analysis?
I found this example in MATLAB https://www.mathworks.com/help/matlab/math/fft-for-spectral-analysis.html and I saw that they use...

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

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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 ...

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

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Find max
Find the maximum value of a given vector or matrix.

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

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Flip the vector from right to left
Flip the vector from right to left. Examples x=[1:5], then y=[5 4 3 2 1] x=[1 4 6], then y=[6 4 1]; Request not ...

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Arrange Vector in descending order
If x=[0,3,4,2,1] then y=[4,3,2,1,0]

Question

How to draw multiple surface plots on the same mesh?
I use this code to draw a Gaussian normal distribution. I want to plot several distributions at equal distance from the original...

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Question

How to calculate the diameter of 3D Gaussian normal distribution?
I want to calculate the diameter of this gaussian distribution. Is there any simple mean to do so?

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Question

Any code for Gaussian beams diffraction through a rectangle aperture?
Suppose I have a rectangle aperture and I want to make Gaussian beams to sufficiently sample this aperture. Is there any code to...

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Magic is simple (for beginners)
Determine for a magic square of order n, the magic sum m. For example m=15 for a magic square of order 3.

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Make a random, non-repeating vector.
This is a basic MATLAB operation. It is for instructional purposes. --- If you want to get a random permutation of integer...

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Create times-tables
At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 times 12 is way more th...

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Roll the Dice!
*Description* Return two random integers between 1 and 6, inclusive, to simulate rolling 2 dice. *Example* [x1,x2] =...

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Determine whether a vector is monotonically increasing
Return true if the elements of the input vector increase monotonically (i.e. each element is larger than the previous). Return f...

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Number of 1s in a binary string
Find the number of 1s in the given binary string. Example. If the input string is '1100101', the output is 4. If the input stri...

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Return the first and last character of a string
Return the first and last character of a string, concatenated together. If there is only one character in the string, the functi...

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Getting the indices from a vector
This is a basic MATLAB operation. It is for instructional purposes. --- You may already know how to <http://www.mathworks....

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Finding Perfect Squares
Given a vector of numbers, return true if one of the numbers is a square of one of the other numbers. Otherwise return false. E...

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Sum all integers from 1 to 2^n
Given the number x, y must be the summation of all integers from 1 to 2^x. For instance if x=2 then y must be 1+2+3+4=10.

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Swap the first and last columns
Flip the outermost columns of matrix A, so that the first column becomes the last and the last column becomes the first. All oth...

Question

Can I simulate this example (diffraction pattern) on my CPU not my GPU?
I tried to apply this example but it doesn't work, because I don't have an external Nividea GPU, I have an intel internal GPU. ...