Group Abstract Group Abstract

Message Boards Message Boards

Beginner needs help

GROUPS:
This is giving me a logical value for my boundary condition equations.  It's not solving my equations.  Where did I go wrong?
Attachment

Attachments: Capture.JPG
POSTED BY: Bob Bixler
Answer
3 months ago
it can read
..., z, {x,1,1},{y,1,1}]

not much space left. Take an unit square instead for the independent variables.

One gets explanations for the messages in the help ref/message/NDSolve/deqn, so a derivative on the boundary is not specified by
D[z[x,0],y]==0
because that gives True (z[x,0] does not depend on y), but using
(D[z[x,y],y]/.y->0)==0
if done so one has
In[108]:= NDSolveValue[{D[z[x, y], {x, 4}] +

    2 D[z[x, y], {x, 2}, {y, 2}] + D[z[x, y], {y, 4}] == q/d,
  z[x, 0] == 0,
  z[0, y] == 0, (D[z[x, y], y] /. y -> 0) ==
   0, (D[z[x, y], x] /. x -> 0) == 0 }, z, {x, 0, 1}, {y, 0, 1}]

During evaluation of In[108]:= NDSolveValue::ivone: Boundary values may only be specified for one independent variable. Initial values may only be specified at one value of the other independent variable. >>

now one reads ref/message/NDSolve/ivone and considers the type of the equation, especially it states

The partial differential equation solver used by NDSolve is designed to solve initial value problems.

purely elliptic problems are not in the scope of NDSolve[], if I understand it right.
POSTED BY: Udo Krause
Answer
3 months ago
Udo, thanks for taking the time to help me.  That means a lot to me.  I'll just code these equations in a general purpose programming language. 
Bob.
POSTED BY: Bob Bixler
Answer
3 months ago