Ahmed A. Selman

University of Baghdad

Last seen: alrededor de 2 meses hace | Con actividad desde 2013

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Ph.D. in theoretical nuclear physics, author of four books and assistant professor at the College of Science-University of Baghdad since 2008. IAU Member since 2021. Recently working on nuclear astrophysics of stars. Interested with image processing applications in astronomy. I begun using Matab since the year 2000 (I think it was ver.5.0), and still there is much to learn about. Google Scholar: https://scholar.google.com/citations?user=TwoAY4wAAAAJ IAU: https://www.iau.org/administration/membership/individual/20684/

Programming Languages:
MATLAB
Spoken Languages:
English, Arabic
Pronouns:
He/him
Professional Interests:
Mathematics, Physics, Gravitation, Cosmology & Astrophysics, Particle & Nuclear Physics

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Optimize loop to reduce run time
Inside the loops of ii and jj, try to move the lines that do not depend on ii out of that loop. It might help to improve some r...

2 meses hace | 0

Respondida
Help naming text file according to user input
Just add the extension you like to the variable (fileName), as prompt = 'Please enter the file name: '; fileName = input(...

alrededor de 11 años hace | 4

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how to find the second order partial derivative of an image?
See older and similar question here: <http://www.mathworks.com/matlabcentral/answers/67893>

alrededor de 11 años hace | 0

Respondida
Reshape array for 256 by 256 matrix showing 16 by 256
Dear sudipta, I have downloaded your data file, and went like a=load('1372387722318.txt'); y=reshape (a,256,256); ...

alrededor de 11 años hace | 0

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Save 512x512 matrix to text file
This code works perfectly. To check it add the following at the very end of the above code: fid = fopen('Mymatrix.txt','r'...

alrededor de 11 años hace | 0

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solve 2 equation of 2 unknown
Use the code instead: clc clear syms theta3 r1 %sind(theta3) % NOT NEEDED r2=3; r3=3.927; r4=0.335; ...

alrededor de 11 años hace | 1

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extracting submatrices from cell
Try the same example with: X={1, 'a'; 'b', 3.14}; K1=X(2,:) [K21 K22]=X{2,:} Then use whos to...

alrededor de 11 años hace | 0

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Respondida
How to identify boundaries of shapes in an image using the change in color
There are few files in the file-exchange <http://www.mathworks.com/matlabcentral/fileexchange/> so do some search there, you mig...

alrededor de 11 años hace | 0

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error message using polynom
A polynomial P(x) is said to be (badly conditioned) when a small variances of x leads to large errors of P, causing unstable err...

alrededor de 11 años hace | 0

Respondida
Creating a matrix with matrices on the sub and super diagonals
Use the command (diag) for creating a (main) diagonal matrix from a vector A, and the command (spdiags) to create sub- and super...

alrededor de 11 años hace | 0

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Picking out a value from a Vector in a Loop iteration
Within your same code: ... plot(Y(:,1),Y(:,2),'o'); z=zeros(1,length(X)); % Add this for i = 1:length(X) f...

alrededor de 11 años hace | 0

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More help with probability...
Just pay attention to how you use function call inside a program. Either you have two files as stated above, or use one main (ca...

alrededor de 11 años hace | 0

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Respondida
How to plot with a logarithmic scale?
semilogx(x,y)

alrededor de 11 años hace | 2

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how to solve loops conditions ??
#1) Using for loops only: clear k=0; for i=1:6 for j=1:5 k=k+1; A(i,j)=k; end end ...

más de 11 años hace | 0

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Symbolic expressions: abs(x^(1/3)) =?= abs(x)^(1/3)
Some times we get confused between mathematics and programming, it is an often thing. Yet, mathematics means logic, programs try...

más de 11 años hace | 0

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how to write a .dat file in matlab?
The obvious method is to construct a loop to read filenames, inside it, open and read, then accumulate the data content in some ...

más de 11 años hace | 0

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Reading many files in one loop
Download a function file called folderFiles.m. <http://www.mathworks.com/matlabcentral/fileexchange/40877-folderfiles-m> ...

más de 11 años hace | 0

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How to read a text file line by line?
Try selecting one dimension a time for each line, e.g., ... time=fscanf(fID,'%g',[1 1:2:inf]); acce=fscanf(fID,'%g',[...

más de 11 años hace | 0

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Obtaning a matrix with the right indexes
Try this out to see if it solves the issue: clear clc N=20; %for example H=sym(zeros(N,4)); B=1:N; ...

más de 11 años hace | 0

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How to create a nested for loop to create a mesh plot
I'm not sure what are your conditions (in the if statements), but you used (y1) as a matrix index which cannot be made unless (y...

más de 11 años hace | 0

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Hi all, could you please help me to solve this equation either numerically of symbolically.
If all variables other than (y) are known, then let's write some notes here: 1) Try to first define the variables, namely: kw...

más de 11 años hace | 0

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Issue with writing multiple variable to excel sheet
It is not practical to write a single line in an excel file, for a large amount of data or inside a long-time running loop. If y...

más de 11 años hace | 1

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while loop question number 2
In such a case, using a while loop cannot do the job, but an if statement can. So, I think this is what are you looking for (con...

más de 11 años hace | 0

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How to plot a complicated function
It is the same code you wrote, only add loops over c and tau, and use the function (ezplot) to plot a function handle. And DO NO...

más de 11 años hace | 0

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how to code probability in general??
First what is magic(2)? I thought the smallest magic matrix comes (3-by-3) since Magic (2) doesn't satisfy the condition (sum ea...

más de 11 años hace | 0

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Lighting the Solar System - Omnidirectional light source (Sun)
I don't know really if Matlab is used for such tasks, but haven't you tried Simulink for easier handling of the problem? Such gr...

más de 11 años hace | 0

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while loop in data file for trapz?
Apparently, the variable (Num) is not (1). That's why the (while loop) returns nothing. I've tried the lines you posted and it w...

más de 11 años hace | 0

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Switch columns in a matrix without a loop
for exchanging two columns 3 - 9 : A = randi(20,4,10); % A random 4 by 10 matrix of integers A(1,:)=[1 2 3 4 5 6 7 ...

más de 11 años hace | 0

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I WANT TO SOLVE THE EQUATION for x: x*exp(x)=(a1-x)*a2*a3 . Here a1 and a3 are matrices and a2 is a constant. I cant solve the equation using solve
True, indeed. Not only for (A,B) = (11,13) and (3,-6), but for a wide range of other set, including the given coefficients.....

más de 11 años hace | 0

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I WANT TO SOLVE THE EQUATION for x: x*exp(x)=(a1-x)*a2*a3 . Here a1 and a3 are matrices and a2 is a constant. I cant solve the equation using solve
The equation you wrote is x*exp(x)=(a1-x)*a2*a3 y= x*exp(x)-(a1-x)*a2*a3 y= x*exp(x)-a1*a2*a3 +x*a2*a3 Let: a1*...

más de 11 años hace | 0

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Ahmed A. Selman

University of Baghdad

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