@Rouben Rostamian  tnx for quick answer,actually, the problem is finding constants, so as you said, the boundary conditions for this problem should be fixed and then , we should find the constants... 
can we fit the answer to spcefic diagram ? for finding the constants..

@Ramakrishnan 
http://www.mapleprimes.com/questions/150659-How-To-Plot-With-The-Results-Of-Desolve-Command

@vv y is positive... why t should be x ? it can not solved assuming x as a constant number ?

@vv when x and y are between numbers about -100 and 100 this circle like diagram is included ! but when the range is changed to -10000 and 10000 this is not ! why it is happening ?!


 

Download solveee.mw

@vv why y is positive? why y>0 ?

@Sergey Moiseev i know this is a package and i have installed it, but where is this package help ?! and descriptions ?

@Sergey Moiseev whats does options means? i can not search  them in maple help...
 checkexit=10 ?

@tomleslie tnx for your quick answer, please change it to an answer , tnx alot.

@Adri van der Meer tnx for your answer , but actually i want the value for all unknown parameters which will maximize the PP;
i.e, what will be the values for, theta[1],theta[2],phi[1],phi[2],p in which the expression pp will be maximized ?

@ecterrab really thank you,i really appreciate your complete answer. I think i need to read help more delicately. Tnx

@ecterrab tnx for your quick and complete answer. actually from your complete description i got the answer, as i think , this derivative :  d_[nu](Psi(X))  converts scalar function Psi(X) to a vector or first order tensor is that right ? how can i recognize a sacalar from tensor in maple ? is there any command in maple for recognizing that?

@ecterrab i think you misunderstood my opinion. 

at first i should appreciate your good work and maple staffs. actually i think maple is one of the best mathematical softwares and i suggest using this to as many people as i can. The most important and unique feature of maple is here, this site ! As far as i know, Maple it the only software on the planet that people can talk directly to staff. and it is the most important parameter for choosing a software in my opinion...

if i said my suggestion it was just and just for the software to get better ... and not for my needings,,,, and as u said, it was not for thing that i wanted !

afterall, i really happy to get familiar with maple, with professional programmers and with respecftul staffs like u. actually it is an honor for me talking directly with professional staffs like you.
please accept my respecftul apologize if i gave my opinion in a wrong way.
sincerely yours...

M.Jafari
Ph.D candidate of Mechanical engineering field.
SUT.

@Axel Vogt it is interesting when using simplify(exp(a)*exp(b)*exp(c), {a+b+c=0}); it does not returns 1 ! and it needs an extra simplification !

Download interesting.mw

@ecterrab can this type of assumption for functions that can test their arguments for assumptions be included for all type of functions in next versions ?! for example for trangular functions , exp , logarithm and ,,,, ?
i think it will be great for physics package !

@vv really tnx, it is working perfectly