Error Flashcards
1
Q
What is the expression for error in the L2 norm?
A
sqrt(int(u(x) - u_exact(x))dx)
2
Q
How is the energy norm different to the L2 norm?
A
The integral is multiplied by E/2
The u(x) and u_exact(x) are differentiated
The subtraction is squared
3
Q
Why are error norms used?
A
They ensure the root is non negative and that errors do not cancel
4
Q
What is h adaptivity?
A
Decreasing element size to reduce error
5
Q
What is p adaptivity?
A
Increasing the polynomial order of the shape functions to reduce error
6
Q
What is the relationship of L2 error to h and p?
A
|e|L2 is proportional to h^(p+1)
7
Q
What is the relationship of energy error to h and p?
A
|e|en is proportional to h^p
8
Q
Name two sources of error in the FEM
A
Geometric error
Solution profile error
