@tomleslie actually diff(x(t),t)=A(t) as u have defined, can i use directly A(t) ? even i used :
int(eval(A(t),ans),t=0..1); but it does not computed ...

odeProb.mw

@tomleslie i want to fit a function to these three plots...
i used polynomial interpolation (CurveFitting:-PolynomialInterpolation([seq]([t, (eval(B(t),ans))(t)],t=0.1..1,0.1),t)).
but it does not give the functions, i think it can be fitted using trigonomic functions, but actually i don't know how, could u help ?
and actually i want to calculate the integral :
int(a1*diff(x(t),t) +a2*diff(y(t),t)+a3*diff(z(t),t) );
can i calculate this without interpolating the functions? tnx for the help...
odeProb.mw

@tomleslie thanak you, and i made use of these deriavatives...

@tomleslie that was interesting idea ! tnx for the help ! Good Luck !

@Mariusz Iwaniuk tnx for your help,where in the help i can find answers for these questions? could please give me a link of the related halp page? tnx

@rlopez tnx for explanation, you are right sir

@tomleslie tnx for your answer,it was helpful, but under "Supplemental Software" there is NOT any help document for maple toolbox...
as u can see in the uploaded picture...
and for the prettyprint option, you say this is just a limitation of using maple in matlab and can not be cured right?

@saba you should specify boundary conditions and other constants and after that, i think you will get desired answer

@tomleslie i guess that the problem is with independent variables, i guess W and Phi are functions of both " x " and " z "

@torabi if it has phi(z) it is pde ! not ode ! but i assume you should define function of Z , as a parametr , then solve your equations and after that ! solve your pramater.

in your equation, phi is function of z ! but in intergal and thus should be solved ! and then you should solve your ode system ! 

@tomleslie 
https://en.wikipedia.org/wiki/Weighted_space

@tomleslie tnx for your help, but your answer is some what different from @Axel Vogt's answer ...

@Axel Vogt tnx it helped and answered, 

@tomleslie i think i have uploaded wrong version, and i will edit and also upload here , and all the problems with unassigned symbols,have been corrected.
i want a closed form solution and plot the result, is that equivalent to evaluate integral numerically and plot the resulting points? if the answer is yes, how can we plot numerical integration?

corrected.mw