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pik1432

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These are questions asked by pik1432

Re: How to collect using a term by multi...

pik1432 245 Maple 2022
multiplication syntax collect
June 02 2022
2 6

Hello there, 

Would you allow me to ask this question?

Is there any way to apply 'collect' command using a term by multiplication of variables?

The following worksheet shows an example. What I wanted to see is the 'desired' expression, while multiple attempts with 'collect' command failed. 


 

> 

restart;
> 

eq_e5_10z := Psi[q0]*Delta*delta = 1/(omega[0])*p(Delta*Psi[q])+Delta*Psi[d]+Psi[d0]*1/(omega[0])*p(Delta*delta);

Psi[q0]*Delta*delta = p(Delta*Psi[q])/omega[0]+Delta*Psi[d]+Psi[d0]*p(Delta*delta)/omega[0]

 (1)
> 

eq_e5_10za := Delta*Psi[d] = Psi[q0]*Delta*delta - op(1, rhs(eq_e5_10z)) - op(3, rhs(eq_e5_10z));

Delta*Psi[d] = Psi[q0]*Delta*delta-p(Delta*Psi[q])/omega[0]-Psi[d0]*p(Delta*delta)/omega[0]

 (2)
> 

eq_e5_10zb := subs({p(Delta*Psi[q])=0}, eq_e5_10za);

Delta*Psi[d] = Psi[q0]*Delta*delta-Psi[d0]*p(Delta*delta)/omega[0]

 (3)
> 

collect(rhs(eq_e5_10zb), {Delta*delta});# error

Error, (in collect) cannot collect Delta*delta

  
> 

collect(rhs(eq_e5_10zb), [Delta*delta]);# error

Error, (in collect) cannot collect Delta*delta

  
> 

collect(rhs(eq_e5_10zb), [Delta, delta]);# did not work  

Psi[q0]*Delta*delta-Psi[d0]*p(Delta*delta)/omega[0]

 (4)
> 

Desired := (psi__q0 - psi__d0*p/omega__0)*(Delta*delta);

(psi__q0-psi__d0*p/omega__0)*Delta*delta

 (5)
> 

 


 

Download Q20220602.mw

RE: How to apply 'diffop2de()' command t...

pik1432 245 Maple
differential-equations duplicate-question diffop2de
April 25 2022
1 7

Hello there, 

Would you allow me to ask this one question?

Is it possible to apply diffop2de() to three different functions in a single expression? For example, the attached worksheet shows an expression, 'eq_e5_9', where three time domain function derivatives are defined, D*Delta__delta(t), D*Delta__psi__d(t) and D*Delta__psi__q(t). However, once 'diffop2de(eq_e5_9, f(t))' is applied, none of them gets propely unrolled (e.g, D*Delta__delta(t)becomes d/dt*Delta__delta(t))

Besides, this is my third time attempting to post a question. The first one got disappeared with no sign, the second one came out with a site error message. 

In Kwon Park 

> 

 

Download Q20220425.mw

Re: How to pick up 'LPSolve' result...

pik1432 245 Maple
April 16 2022
1 2

Hello all, 

Is there any chance to ask these two questions?

1) What would be the way to pick up the result from 'LPSolve' command? I thought that the command would overlay the result to the input matrix, but I was wrong. 

2) This question is not related to Maple, but I saw that the transportation problem described in the attached worksheet has multiple solutions. In other words, the solution that came up with 'LPSolve' command was different from what the textbook presented, but both of them were legitimate solutions. Therefore, I'm wondering if there is a way to test the uniqueness of the solution. 

In Kwon Park 

Q20220416.mw

 

Re: How to treat differentiaion operator...

pik1432 245 Maple 2020
differentiation operator
April 04 2022
2 13

Hello all, 

Would you allow me to ask this one question?
[moderator: See also this previous question]

Is there any possible way to treat the differentiation operator (e.g., 'D') as an ordinary coefficient of a polynomial?

For example, as described in the attached worksheet, I was wondering if there is a way to re-write the LHS of the expression 'eq_e5_9b' as the expression 'desired'. 

In Kwon Park 

> 

restart;
> 

with(DEtools):
> 

eq_e5_9b := psi__d0*Delta__delta(t) + psi__q0 * D(Delta__delta(t))/omega__0 = p_(Delta__psi__d(t))/omega__0 - Delta__psi__q(t);

psi__d0*Delta__delta(t)+psi__q0*D(Delta__delta(t))/omega__0 = p_(Delta__psi__d(t))/omega__0-Delta__psi__q(t)

 (1)
> 

collect(lhs(eq_e5_9b), Delta__delta(t));

psi__d0*Delta__delta(t)+psi__q0*D(Delta__delta(t))/omega__0

 (2)
> 

desired := Delta__delta(t) * (psi__d0 + psi__q0 * D/omega__0);

Delta__delta(t)*(psi__d0+psi__q0*D/omega__0)

 (3)
> 

 

Download Q20220404.mw

Re: how to preserve '1d' subscript as is...

pik1432 245 Maple 2020
subscript
January 21 2022
2 6

Hello there, 

When I tried to write an expression with the '1d' subscript, I found that it was automatically translated as '1.'. The following worksheet shows an example. Is there any chance to preserve the expression as I intended to see?

> 

restart;
> 

eq3_130:= Psi[fd] = L[ffd]*i[fd]+L[f1d]*i[1d]-L[ad]*i[d];

Psi[fd] = -L[ad]*i[d]+L[f1d]*i[1.]+L[ffd]*i[fd]

 (1)
> 

 

Download Q20220121.mw

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