# Where is the problem ? (NDSolveValue, Poisson equation)

I have a rectangular region: {x,0,1},{y,0,2}, with Neumann conditions on the left and on the right sides and Dirichlet conditions on the others.

Everything works without errors until NDSolveValue.

I get an error:

"PDE parsing error (...). Inconsistent equation dimensions."


Need help in fixing the problem or a piece of advice what to google. Thanks in advance.

$$u(x_{min}, y) = \sin(y^2)$$ $$u(x_{max}, y) = \cos(3y)$$ $$\left.\dfrac{du}{dy}\right|_{x,y_1} = 10\sin(x^2)$$ $$\left.\dfrac{du}{du}\right|_{x,y_m} = 10\sin(6x)$$

Ω={{x,0,1},{y,0,2}}

(* {{x,0,1},{y,0,2}} *)

op=D[u[x,y],{x,2}] + D[u[x,y],{y,2}]-Exp[-x]-Exp[-y]

(* -E^-x-E^-y+(u^(0,2))[x,y]+(u^(2,0))[x,y] *)

Subscript[Γ,D]={DirichletCondition[u[x,y]==Sin[y^2],x==0 &&  0<=y<=2],DirichletCondition[u[x,y]==Cos[3y],x==1 && 0<= y<= 2]}

(* {DirichletCondition[u[x,y]==Sin[y^2],x==0&&0<=y<=2],DirichletCondition[u[x,y]==Cos[3 y],x==1&&0<=y<=2]} *)

Subscript[Γ,N]={NeumannValue[10*Sin[x^2],0 <= x<= 1 && y==0 ] , NeumannValue[10*Sin[6x], 0<= x <= 1 && y==2] }

(* {NeumannValue[10 Sin[x^2],0<=x<=1&&y==0],NeumannValue[10 Sin[6 x],0<=x<=1&&y==2]} *)

ufun=NDSolveValue[{op==Subscript[Γ,N],Subscript[Γ,D]},u,{x,0,1},{y,0,2}]

(* During evaluation of NDSolveValue: PDE parsing error of {{-E^-x-E^-y+u$8832+u$8833-NeumannValue[10 Sin[x^2],0<=x<=1&&y==0],-E^-x-E^-y+u$8832+u$8833-NeumannValue[10 Sin[6 x],0<=x<=1&&y==2]}}. Inconsistent equation dimensions. *)

• Just a comment: never use capital letters, especially D or N as a variable names. It's a Wolfram functions. – m0nhawk Sep 8 '16 at 19:32
• also get rid of all that subscript stuff. causes more trouble than worth it. I have no idea what Subscript[Γ,D]={DirichletCondition[u[x,y].... is supposed to be or do. – Nasser Sep 8 '16 at 19:49

ufun = NDSolveValue[{D[u[x, y], {x, 2}] + D[u[x, y], {y, 2}] - Exp[-x] - Exp[-y] ==