Ahmed A. Selman

University of Baghdad

Last seen: 9 mesi fa | Attivo dal 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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Risposto
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...

9 mesi fa | 0

Risposto
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(...

oltre 11 anni fa | 4

| accettato

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

oltre 11 anni fa | 0

Risposto
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); ...

oltre 11 anni fa | 0

| accettato

Risposto
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'...

quasi 12 anni fa | 0

Risposto
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; ...

quasi 12 anni fa | 1

| accettato

Risposto
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...

quasi 12 anni fa | 0

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Risposto
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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 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...

quasi 12 anni fa | 0

| accettato

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

quasi 12 anni fa | 2

| accettato

Risposto
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 ...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

Risposto
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 ...

quasi 12 anni fa | 0

| accettato

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

quasi 12 anni fa | 0

| accettato

Risposto
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',[...

quasi 12 anni fa | 0

Risposto
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; ...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

| accettato

Risposto
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...

quasi 12 anni fa | 0

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Risposto
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...

quasi 12 anni fa | 0

Risposto
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...

quasi 12 anni fa | 0

Risposto
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 ...

quasi 12 anni fa | 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.....

quasi 12 anni fa | 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*...

quasi 12 anni fa | 0

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Ahmed A. Selman

University of Baghdad

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