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# zhenyu zeng

13 total contributions since 2019

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Question

What is the difference between them?
These code are right: a=0.336; Ta=9.476; Te=1.208; Tw=1.498; eqh=[0.661;0.619;0.568]; ex=[-1.24;-1.346;-1.441]; en=-ex; ...

5 jours ago | 0 answers | 0

### 0

Question

How to solve inequality group and plot color block？
For example: x*y+x*y^2+x*y^3+x^3*y<2 x*y+x*y^7+x^2*y^-5>9 (x+y^2)*x^2*y^-2>10 How can I slove ths inequality group by matl...

6 jours ago | 0 answers | 0

### 0

Question

There is an error in the Matlab document
C=gallery('uniformdata',[5 4], 0); [Q,R] = qr(C); [Q,R] = qr(C,0); [Q,R,P] = qr(C) Q = -0.3522 0.8398 -0.4131 -0...

environ 2 mois ago | 0 answers | 0

### 0

Question

Why must have brackets around 'student'?
function avg=avgscore(testscores,student,first,last) for k=first:last scores(k)=testscores.(student).week(k); end avg=su...

environ 2 mois ago | 1 answer | 0

### 1

Why the last row is wrong？
Wrong： sym.charToFunction (line 26) Invalid variable name. Wrong： sym/collect (line 40) x = sym.charToFunction(x);

3 mois ago | 0

Question

Why the last row is wrong？
t=sym('t','positive') ut=str2sym('Heaviside(t)-Heaviside(t-1)') ht=t*exp(-t) yt=int(subs(ut,t,tao)*subs(ht,t,t-tao),tao,0,t) ...

3 mois ago | 1 answer | 0

### 1

Question

What is the meaning of 'simplify(n./d)?
What is the meaning of 'simplify(n./d)? I feel n./d is weird. syms x A=[3/2 (x^2+3)/(2*x-1)+3*x/(x-1);4/x^2,3*x+4] pretty...

3 mois ago | 1 answer | 0

### 1

Question

expr2=collect(EXPR,'exp(-t)') Why is it wrong?
EXPR=str2sym('(x^2+x*exp(-t)+1)*(x+exp(-t))') expr1=collect(EXPR) expr2=collect(EXPR,'exp(-t)') Why expr2 shows: sym.charTo...

3 mois ago | 1 answer | 0

### 1

Question

Why is it wrong: e3=sym('sin(x)^2+cos(x)=0')
Why is it wrong: e3=sym('sin(x)^2+cos(x)=0')

3 mois ago | 2 answers | 0

### 2

Question

four dimensions array's expression
A=rand(2,3,3) B=cat(4,A(:,:,1),A(:,:,2),A(:,:,3)) B(:,:,1,1)= B(:,:,1,2)= B(:,:,1,3)= B(:,:,1,4)= Why not B(:,:,1,1)= B(...

4 mois ago | 2 answers | 0

### 2

Question

What is the meaning of [B,J]=sort(A,'descend')?
What is the meaning of [B,J]=sort(A,'descend') Why can he use [B,J] here?

4 mois ago | 0 answers | 0

### 0

Question

A(B)=0 What is its meaning?
A=rand(5) B=A>0.8 A(B)=0 Can you tell me what is A(B)=0 meaning?

5 mois ago | 2 answers | 0