CyberRob

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These are replies submitted by CyberRob

@Kitonum Your ideal does not yield exactly what I am looking for


coeffs(c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel + (c4*nus0 + c5)*dnub + dnub, [nur, nub, dnur, dnub, nurdel, nubdel, dnurdel, dnubdel], 't');

t;
             

c4 kpbr ksr, c4 kpbr ksr, c4 nus0 + c5 + 1

nurdel nur dnub, nurdel nub dnur, dnub

 

@acer Thanks for your answer. To make my question preciser: I have a Multivariate Polynomial Ring in nur, nub, dnur, dnub, nurdel, nubdel, dnurdel, dnubdel over Multivariate Polynomial Ring in kpr, kpbr, nup0, ksr, ksbr, nus0, c4 and c5 over Rational Field. Then I have an element of this ring, lets say

c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel + (c4*nus0 + c5)*dnub+dnub

I would like to extract all the coefficients and  monomials. In this case I get for the monomials

m=[nub*dnur*nurdel, nur*dnub*nurdel, dnub, 1]

and for the coefficients

c=[c4*kpbr*ksr, c4*kpbr*ksr, c4*nus0 + c1 + c5]

However, I look for a way to get a list of monomials without redundant elements such that

m=[nur*dnub*nurdel+nur*dnub*nurdel, dnub, 1]

and

c=[c4*kpbr*ksr, c4*nus0 + c1 + c5]

 

@Kitonum This works only for simple examples. If I make my example more complicated, lets say

c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel + (c4*nus0 + c5)*dnub+dnub

The simplify command returns

((kpbr*ksr*nur*nurdel + nus0)*c4 + c5 + 1)*dnub + c4*dnur*kpbr*ksr*nub*nurdel

But I would like to have is

c4*kpbr*ksr*nurdel*(dnub*nur + dnur*nub) + (c4*nus0 + c5+1)*dnub;

 

 

@Carl Love @Kitonum 's solution is still very special. If I change the initial expression

c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel

to

c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel + nub

The proposed solution

A := factor(c4*dnub*kpbr*ksr*nur*nurdel + c4*dnur*kpbr*ksr*nub*nurdel + nub)

does not work anymore. For this example I would expect a solution that yields

c4*kpbr*ksr*nurdel*(dnub*nur + dnur*nub)+nub

 

@Kitonum In your solution you use some knowledge about the expressions, for instance in

op(1..3,A)).

However, I would like to find a solution where no nowledge about the expression is needed. The problem I forumulated is extracted from a more complicated expression where I can not use this approach.

@Kitonum 

Thanks!

@Kitonum Thanks for your fast answer! i am a beginner in Maple. Could you briefly explain how these commands solve the problem?

 

@Kitonum there was a Typo in my first question. I corrected it

@vv 

Thanks for your fast answer. So What I want to do is the following: I have the known functions x1, x1[t], x1[t,t] and ke. The parameter k12, k21 and Ve are unknowns. I want to rearrange the equation such that I have expressions involving the unknows, ie,  k12, k21 and Ve, multiplied by expressions involving the known functions, ie, expressions involving  x1, x1[t], x1[t,t] and ke.. The goal is to rearrange the equations such that the combinations of unknows can be estimation using a LS-optimization.

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