Message Boards Message Boards

0
|
4856 Views
|
2 Replies
|
1 Total Likes
View groups...
Share
Share this post:

Beginner needs help

Posted 11 years ago
This is giving me a logical value for my boundary condition equations.  It's not solving my equations.  Where did I go wrong?
Attachments:
POSTED BY: Bob Bixler
2 Replies
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
Posted 11 years 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
Reply to this discussion
Community posts can be styled and formatted using the Markdown syntax.
Reply Preview
Attachments
Remove
or Discard

Group Abstract Group Abstract