# Wan Ji

### Wuhan University

Research Interest: computational mechanics and modeling the world

**Programming Languages:**

Python, C++, C, MATLAB, Fortran

**Spoken Languages:**

English, French, Mandarin

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**5** Questions

**164** Answers

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RANK**7,507** of 18,589

REPUTATION**113**

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**Content Feed**

How to show node/element numbers on the boundary ONLY?

Hi, friend, Here are some tips for you. Firstly, you can find those edges (an edge is generally denoted by two nodes) that are...

1 year ago | 0

Call a folder from desktop and use images inside it

Hey, friend, Using uigetfile is a nice choice, for example [file,path,indx] = uigetfile( ... {'*.jpg;*.png;*.tiff;*.tif;*.bmp...

1 year ago | 0

| accepted

Question

Matlab default font monospace is not a wise choice

Did anyone encounter a problem when writing an m-script on matlab? The problem is that your naked eyes can't tell the number '1'...

1 year ago | 1 answer | 0

### 1

answerHow can I fix my function?

Hey， friend Just try the inline function ispythag = @(a,b,c)a.^2+b.^2 == c.^2; a = ispythag(1,2,3) b = ispythag(3,4,5) Then...

1 year ago | 0

| accepted

Matlab versions supported on Windows 11?

WINDOWS 11 itself should support running the softwares on win10. ELSE microsoft would not release it and clients would not use i...

1 year ago | 0

Using ODE45 for first order diff equation with three different variables

For example function dxdt = func(t,x,g) dxdt = zeros(3,1); dxdt(1) = (0.1*x(1))+(0.25*x(2))-(g*x(3)); dxdt(2) = (0.1*x(1))+(...

1 year ago | 2

| accepted

how to write to solve this type of system of equations ?

Hey friend Just expand the left items of the two equations, extract u'' and v'', then an ode45 solver is there for you.

1 year ago | 0

multiple graphs in one script

Modified the code as %% 6 x = ([-2*pi:0.1:2*pi]); f = x-sin(x) g = 1-x.*cos(x) figure(1);clf; plot(x,f,x,g) title('f(x) &...

1 year ago | 0

How to check if an array is empty without using any built in functions

Use isempty x = []; isempty(x) Then the answer is ans = logical 1

1 year ago | 1

| accepted

I want to co-relate the local coordinate system with global co-ordinate system of a 8-noded element. How to do it in matlab?

You need to add the element information element_id = 5; % for example, the local element id is 5 selected_element = element(el...

1 year ago | 0

| accepted

Question

I don't know how to avoid eval

Hi friends from community, I am very confused on how to manage 'eval' function existing in my code, i need it to be removed fro...

1 year ago | 3 answers | 0

### 3

answersTotal Solution Differential Equation

If u(t) = 1, then your solution is right. If it is a function with respect to time, then your solution is wrong. Exact code: ...

1 year ago | 0

How to plot such figure in MATLAB?

use polarplot theta = 0:0.1:pi; r = 1+0.6*sin(10*theta); polarplot(theta,r); set(gca,'ThetaLim',[0 180]) set(gca,'Rdir','re...

1 year ago | 1

| accepted

How to plot a 3D vortex flow

If you donot have a mesh, then you need to reconstruct your mesh! X = X(:); Y = Y(:); Z = Z(:); U = U(:); V= V(:); W=W(:); min...

1 year ago | 0

| accepted

Saving the regression trained model

You should save the trained model after click the 'export' the model to workspace. (you can see you saved model in workspace) ...

1 year ago | 0

| accepted

Solving 3 simultaneous equations using solve.

Do not use 'pi' use pi instead %define attributes: gamma=21.05; phi=35.55; phi1=0.75*phi; d=0.6; syms L Rs Rb; zc=(0.3*ph...

1 year ago | 0

How to add consecutive numbers from a column in a .txt file?

Just use movsum a = [1 1 8 2 3 1]; b = movsum(a,2); % I should apologize for not adding 2 b = b(2:end) The answer b = ...

1 year ago | 1

| accepted

How do i write the function for the taylor polynomial of cos(x) using for loops and no anonymous function

If a large x is selected, then use function Pn = taylor_cos(a,n) x=mod(abs(a),2*pi); % if(x>=pi) x = 2*pi-x; end Pn=1;...

1 year ago | 0

| accepted

How to use sym and function handle(@) in same code

Hi, use matlabFunction, my friend syms theta Ai = cos(theta).*[1 1 2; 4 5 6; 9 1 3] Bi = tan(theta).*[6 9 1; ...

1 year ago | 0

| accepted

How to average first two dimension of 3D array/matrix?

Just use mean function to average first two dimension of 3D matrix a = rand(2,3,4); % I just use rand function so the result is...

1 year ago | 1

Save points or data in right order

I have answered this question before, now I have a better solution to this problem which can identify many connected regions cl...

1 year ago | 0

| accepted

How to make a={'1','2','3','4'} to b={'1234'}

The simple way is a={'1','2','3','4'}; b = {[a{:}]} Answer b = 1×1 cell array {'1234'}

1 year ago | 0

| accepted

how do you sum using loop?

x=1:100; f=@(x)x.*(1+x); S=sum(f(x));%this should be ok %or use loop f=@(x)x.*(1+x); S=0; for i=1:100 S=S+f(i); end...

1 year ago | 0

How to form a sphere with 1's in a 3D matrix

If there is no scale factor effect with different directions: m = 80; n = 100; p=90; [px,py,pz] = meshgrid(1:n, 1:m, 1:p); ra...

1 year ago | 1

| accepted

How to sum the values when they are bigger than 25, 50, 75, (conditional) and they are from the same group?

That's quite simple, you don't need to compare them clc;clear ID = ['1_A' ; '1_A'; '1_A'; '2_B'; '2_B'; '3_C'; '3_C';...

1 year ago | 0

| accepted

How to i change the SNR to Vector?

SNR = -20:10:30; a(numel(SNR)) = helperModClassTestChannel(); for i = 1:1:SNR a(i).SNR = SNR(i); end

1 year ago | 0

Why is it not taking the sqrt function, and how to fix it?

You should transform char format to double then do your work B = str2num(B); H = str2num(H); n = str2num(n); s = str2num(s);...

1 year ago | 0

plot the equation graph

Hi, It is not neccessary to solve this equation x = 0:0.00001:1; f = @(x,m,a)(m*pi+atan((x)/(1-x))+atan((a+x)/(1-x)))./sqrt(1...

1 year ago | 0

How to plot mean with respect to bins?

Hi friend, Use histcounts and histogram, then the work is done clc;clear value = rand(100,1) + 0.1; % lack of your data, i ge...

1 year ago | 0

hot to plot horizontal Histogram??

Try to do this counts = [0 664 320 316 664 664 664 664 320 320 664 664 664 664 664 240 664 229 664 664]; Substances = 'abcdefg...

1 year ago | 0

| accepted