I cannot plot the **erf** function, please see below, what's wrong ?

Please how do I display these two fields in the euclidian plane:

(X,Y)=(2e_1, e_2)=(2\partial/\partial x_1,\partial/partial x_2)

with their **elements representation** ? What is the appropriate command to display this?

Can I force Maple to solve the 2 variable recurrence from this page:

https://mathoverflow.net/questions/182188/limiting-probabilities-for-two-player-game-drawing-random-uniform-numbers?rq=1

How can I do that? Can I obtain a closed form from Maple?

I want to solve an ODE from Game Theory, the Cournot competition.

It says

p(q1+r2(q1))+p'(q1+r2(q1))*r2(q1)-c2'(r2(q1))=0

 where, I think,

' means diff(,q1),

c2(q2)=c*q2 for a fixed c in [0,1]

and

p(q)=max(0,1-q).

So c2,p and r2 are functions.r2 goes from [0,inf) to [0,inf).

I look for r2, which should be r2(q1)=(1-q1-c)/2 when correctly solved.

However, the command dsolve says Error in dsolve (divison by 0).

 What is wrong? How do I obtain the solution for r2 in Maple?

If I do even expansion for the function 2*x-2, x from [0,1], to the real line,how do I make Maple to produce

the Fourier cosine expansion in the form 2*x-2=a_0/2+Sum(a_n cos n*Pi*x)

?