# Question:Getting maple to output a particular 'prefered way' of displaying a result.

## Question:Getting maple to output a particular 'prefered way' of displaying a result.

Maple

Dear All,

I would appreciate you advice on the following problem. It is related to getting maple to write its output in a cirtain way which the user prefers.

solve((-q*N3*X3)/e3 = (q*N1*X1)/e1 + (q*N2*X2)/e2, X3);

it will produce:

X3 = -((N1*X1*e2 + N2*X2*e1)e3) / (e1*e2*N3)

I can see by inspection that the solution above is equivalent to:

X3 = (-(N1*X1*e2 + N2*X2*e1) / N3) * (e3/(e1*e2))

Which is the prefered way of writing this particular equation in my line of work.

Is there a command or set of commands or method of manipulation that I can use to force maple to display the result in the way I wish? If such a tool exists is there any limitation to its generality (does it work on big linear equations, matrix, ODEs etc.)

I am aware of commands such as collect, simplify, expand, normal, factor etc. which can do what I want in some situations, but they don't allow the level of control that I would like. It can be hit and miss if they give you the form you like or not, in this case they do not. You could expand the solution and then collect for e3 which is quite close, but i don't know how to get e1 and e2 out of the bracket.

I get the feeling that this problem probably has a simple solution, appolgies if this is the case.

Many thanks,

James

Just in case you're wondering:

X1, X2, and X3 are distances of depleation of a space charge region in a semiconductor PIN diode. e1 e2 and e2 are the relative permitivities of the different semiconductor layers and N1 N2 and N3 are the doping densities. P and N type material is denoted by a negation (hence N3 must be different to N1 and N2 as it is negated).  This is not relevent to the problem faced, it is just so you know where the equation comes from. ﻿