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# Yongjian Feng

Last seen: en dag ago Active since 2021

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Animate gradient descent in 3D plot or 2D contour plot. Visualization. Demonstrate impacts of alpha, starting point, saddle po...

Why Matlab does not see Python?
matlab uses PATH env var to find python. Your python installation is in a local path. Try this in matlab command line: getenv('...

ungefär ett år ago | 1

In python, you seem to use read_only flag ("r"). Maybe you want to try: H5F.open('https://dandiarchive.s3.amazonaws.com/blobs/5...

ungefär ett år ago | 0

Create a permutation of elements in the same position
Just 3 for loops.

ungefär ett år ago | 0

Error on loop on multiple ASCII files
File.name only gives you the name of the file, not the path. Try: files=dir('F:\Teamdrive\TEST\**\*.ascii'); numfiles=length(f...

ungefär ett år ago | 0

Matlab plot3 line color setting
Separate them: plot3(x1',z1',y1','Color', myGreen); hold on plot3(x2',z2',y2', 'm', x3',z3',y3','b', x4',z4',y4','k');

ungefär ett år ago | 0

Problem multiplying exponential function with negative value
Try this: t = -20:1:20; x_t = t.*(exp(-0.15*t)); plot(t, x_t)

ungefär ett år ago | 1

Warning: Using only the real component of complex data.
j is the imaginary unit here, so x is complex. stem is not used to plot complex numbers, that is why only the real component is ...

ungefär ett år ago | 0

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Loop calculation and output
You meant this: txtFiles = dir('*.txt') ; l=length(txtFiles); N = l*10 ; Bandsheet = zeros(N,8); PSDSheet1 =zeros(N,16); P...

ungefär ett år ago | 0

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Hello Nicholas, Currently these two settings can't be controlled by the user. One alternative is to use copy and paste. You c...

ungefär ett år ago | 0

RuntimeWarning: Couldn't find ffprobe or avprobe - defaulting to ffprobe, but may not work warn("Couldn't find ffprobe or avprobe - defaulting to ffprobe, but may not work",
Try this on matlab command line window: getenv('PATH') This will tell you what PATH matlab is using. You might need to restart...

ungefär ett år ago | 0

Automatically launching an executable
Looks like a warning from Windows, not from matlab. Try to run matlab as admin.

ungefär ett år ago | 0

Error using subprocess>_execute_child (line 1311) Python Error: FileNotFoundError: [WinError 2] The system cannot find the file specified
Most of the times, this kind of error can be fixed by setting the env var PYTHONPATH inside matlab. So figure out what file/pa...

ungefär ett år ago | 0

how to set x-axis and y-axis of a plot as log scales in bold with latex interpreter?
How about these: ax = gca; ax.XAxis.FontWeight='bold'; ax.XAxis.Scale = 'log';

ungefär ett år ago | 0

how to find the nearest value (if a value is already provided) from a given array?
Try this: x=0.61; m=linspace(0,1,9); [a, b] = min(abs(m-x)); m(b)

ungefär ett år ago | 0

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hi i have vector for i and this equation : i= (K1*V+(K2*V^0.5)) and amount of V in known. how can i found K1 and K2?
If I and V are vectors, you can just call solve to do the job: I = [1 2]; V = [3 4]; syms K1 syms K2 eq = I == (K1.*V+(K2.*...

ungefär ett år ago | 0

plot from ode45
Too many errors in your code. I tried to clean some, but it still has trouble to figure out what y is: function kk1 clear...

ungefär ett år ago | 0

For "automatically loading", you most likely mean generating the file names in a loop? Try this: num_case = 26; files={}; fo...

ungefär ett år ago | 0

How do I print one variable from solve() ?
Just do disp(A); disp(B); Or a complete script: syms A syms B primereq = 18 * A - 8 * B == 0; segundaeq = -1 * A - 18 ...

ungefär ett år ago | 1

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Can I take data while setting them
Not sure how useful the command you proposed is. If you create first a=rand(4) and then take 8 of them as a(:,2:3), the rest 8...

ungefär ett år ago | 2

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execute cell content as lines of command in Matlab
Try this first from matlab command line window: pe = pyenv This will tell you what python env is used by your matlab installat...

ungefär ett år ago | 0

File selection using uigetfile in an App in appdesigner
uigetfile in general is put in a callback for a button, as mentioned by Michael. The ValueChanged callback of a textbox is not a...

ungefär ett år ago | 0

I receive the output "Empty sym: 0-by-1"
Ok, the coefficients are the same for both equations. You basically have A*C_1+B*C_2+C ==0 and A*C_1+B*C2+D ==0. These two stra...

ungefär ett år ago | 1

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3d and 4d plotting
Try this?

ungefär ett år ago | 0

How to call a function inside other function in a equation?
It depends on whether you need to use B in anywhere else. If B is only used in your function yield, you can put it in the same m...

ungefär ett år ago | 0

Sprintf problems while trying to format a directory name followed by a string
Try this: sprintf("\\Mann_Turb\\Seed_%.0f\\class4_10_seed%.0f\\class4_10_seed%.0f_v.bin", 600, 600, 600)

ungefär ett år ago | 0

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Finding the last value of a difference equation
Use: y(end) = -3

ungefär ett år ago | 0