# I Metric for knowing when numerical BC is "good"

#### eys_physics

I think that one usually tries to restrict the solution such that the boundary conditions are exactly (up to round-of errors) satisfied.
For example, if you have an expansion
$$f(x)=\sum_{k=1}^n a_k \phi_k(x)$$ and a condition $f(0)=0$, you can select the basis functions such that the condition is satisfied.
However, I'm not sure if it is possible in your case.

"Metric for knowing when numerical BC is "good""

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving