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### St. Petersburg State University

Last seen: 6 Tage ago Active since 2014

Professional Interests: computational physics, applied mathematics

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How to fit to an infinite series function?
An iterative solution instead of the symbolic one can be more productive this case, like this one x=[0 5 10 15 20 30 45 60 75 9...

10 Monate ago | 0

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Submitted

Wigner 3j-6j-9j
Wigner 3j-, 6j-, 9j-symbols

How to average columns of matrix without loop?
reshape(mean(reshape(A',n,[]))',size(A,2)/n,[])'

11 Monate ago | 0

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When i try this sym('x')^y i get an error message
You cannot compute this directly because the integers are larger than matlab is able to treat. You can try b = sym(log10(18008...

12 Monate ago | 1

How to plot step functions in Matlab
syms x; y=piecewise(x<0,0, 0<=x<2*pi,exp(-x).*cos(x), x>=2*pi,2*exp(-x).*cos(x)); t=linspace(-pi,4*pi,1000); plot(t,subs(y,x,...

etwa ein Jahr ago | 0

Adding or subtracting the same number
n=4; % array length x=zeros(1,n); % sample array d=0.4; % value to be added/subtracted k=rand(1,n); % uniformly random number...

etwa ein Jahr ago | 1

How to plot complicated exponential function 4.82 (1 + 0.35 e^ −4.07t ) / (1 − 0.35 e^−4.07t) on matlab
Use the element-wise division when computing y: y = ((4.8184) * (1 + 0.3497.*exp(-4.0719.*x))) ./ (1 - 0.3497.*exp(-4.0719.*x))...

etwa ein Jahr ago | 1

make different numbers with the same digits
x=1342; y=str2num(sort(num2str(x),'ascend')); % smaller z=str2num(sort(num2str(x),'descend')); % bigger

etwa ein Jahr ago | 0

is it possible to write a code that examine and analyze that a data in vector having 100 values, so recognize that if one or two very high as compare to other data?
This is known as the problem of locating outliers. Various approaches were proposed. E.g., the one based on the median absolute ...

etwa ein Jahr ago | 0

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flip the sign at zero crossing point
Data1 = [1,0,1,1,0,1,1,0,0,1,0,1,0]; k=find(~Data1); if ~isempty(k) if k(end)<numel(Data1) k(end+1)=numel(Data1)...

etwa ein Jahr ago | 0

Issue with 'for' loop - trying to iterate through and change certain values to 0 in array
If the equality must be exact, just x_results(x_results==.3095)=0; and nothing else (sometimes can produce an incorrect result...

mehr als ein Jahr ago | 0

How can I create a script that calculates this combinatorial?
C=nchoosek(n,r)

mehr als ein Jahr ago | 0

Specify eigenvector for eigs
Matlab documentation: 'StartVector' — Initial starting vector random vector (default) | vector Initial starting vector, spe...

mehr als ein Jahr ago | 0

How to "wrap text" on pushbutton string?
Use the cell array with entries containing text fragments to be shown in separate strings.

mehr als ein Jahr ago | 0

how to implement the algorithm for approximating Cosine using the Taylor series
syms theta n=4; taylor(cos(theta),'Order',n)

mehr als ein Jahr ago | 0

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Submitted

aux2bib
BibTex (LaTeX) sublibrary from an AUX file

Is there any way to accelerate the solving of a series of large sparse positive definite linear equations "Ax=b" with same "A" and different "b"?
It depends... Besides inv(A), you can try A\eye(n), pinv(A)--all of them are equivalent for a well-conditioned A and different ...

mehr als ein Jahr ago | 0

Is there any method to calculate the inverse of matrix which changed a few values?
I am not sure how much profitable it is numerically, but the Sherman Morrison theorem can be a way, see https://en.wikipedia.org...

mehr als ein Jahr ago | 1

What does ''all'' mean in M = min(A, []. ''all'') ?
All this is fairly well described in the matlab documentation. min(min(A)) and min(A, [], ''all'') are equivalent for 1D and 2D ...

mehr als ein Jahr ago | 0

If I have multiple function, then how can I get the function of min(fun1,fun2,fun3,...)?
xmin=min([R1(x(:)');R2(x(:)');...]); % to get a correct result, the argument must be a row-vector: x(:)' turns any input array t...

mehr als ein Jahr ago | 0

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Is there a bug in the if function
This is not a bug in the if function but an artefact of the rounding of the matlab bit-wise arithmetics. To avoid this effect, s...

mehr als ein Jahr ago | 0

Angle between two lines in frontal plane
If, as it looks in the figure, (...Y) are the verticle coordinates and (...Z) are the horizontal coordinates, then the basic geo...

mehr als ein Jahr ago | 1

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solve function give a wrong solution
syms x solv = double(solve( (1+x/12)^12 == 1.02)) There are many solutions. The one you are interested in is rather 0.01981897...

mehr als ein Jahr ago | 0

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How to see the current value of the variable in "fminsearch" optimization?
optimset('Display','iter'); From Matlab documentation: 'Display' — Level of display 'notify' (default) | 'final' | 'off' | 'n...

mehr als ein Jahr ago | 0

showing the distance between the two plots on two curves at regular intervals on the same plot
t=0:0.2:10; % avoid loops wherenever possible, use element-wise operations instead x=t.^2; y=0.5*x+10; % the same as "y=0.5*t...

mehr als ein Jahr ago | 0

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Writing into .txt file
T = [v angle_random]; % this is if you want a 2-column file save('random_cylind.txt','T','-ascii','-double'); % explore availab...

mehr als ein Jahr ago | 0

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Debugging using external editor
https://www.mathworks.com/help/matlab/matlab_external/debugging-on-microsoft-windows-platforms.html

mehr als ein Jahr ago | 0

Submitted

aux2bib
BibTex sublibrary from a LaTeX AUX file