Yongjian Feng

Last seen: 1 day ago | Active since 2021

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

1 day ago | 8 downloads |

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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('...

11 months ago | 1

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problem reading HDF5 on s3
In python, you seem to use read_only flag ("r"). Maybe you want to try: H5F.open('https://dandiarchive.s3.amazonaws.com/blobs/5...

11 months ago | 0

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

12 months ago | 0

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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...

12 months ago | 0

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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');

12 months ago | 0

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

12 months ago | 1

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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 ...

12 months 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...

12 months ago | 0

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

12 months ago | 0

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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...

12 months ago | 0

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

12 months ago | 0

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I need to use Newton's method to solve f(x). Can any one tell me what's wrong of my code and how to improve it.
what i s your dx?

12 months ago | 0

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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...

12 months ago | 0

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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';

12 months ago | 0

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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)

12 months ago | 0

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Answered
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.*...

12 months ago | 0

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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...

12 months ago | 0

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

1 year ago | 0

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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 ...

1 year 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...

1 year ago | 2

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Answered
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...

1 year ago | 0

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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...

1 year ago | 0

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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...

1 year ago | 1

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Answered
3d and 4d plotting
Try this?

1 year ago | 0

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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...

1 year ago | 0

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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)

1 year ago | 0

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

1 year ago | 0

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ROS required python packages
Your python installation looks good for ROS. What is the detail of the error message?

1 year ago | 0

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Solve equation including parameters dependent on main variable
k shall be a symbol, once you do this before it is used, then this will take care of the dependency of delta and theta. syms k;...

1 year ago | 0

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