Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Intel Community
- Software
- Software Development SDKs and Libraries
- Intel® oneAPI Math Kernel Library
- Dirichlet Boundary Question

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page

Christos_S_

Beginner

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

01-03-2018
10:08 PM

54 Views

Dirichlet Boundary Question

Hello all,

I am using Intel MKL to solve a Poisson equation for surface smoothing purposes, and I have tried both Neumann and Dirichlet Boundary Conditions. The 2D surface is composed of a grid with small -ve values as default when the grid is empty, and 0, or +ve values when the grid is full.

I have noticed that when I used Dirichlet Boundary Conditions, e.g. a zero or small -ve numeric value, the reported Poisson outcome (smoothed surface) contains large ** negative values** near the four corners of the surface, despite that the original surface is mostly positive (only contains small -ve grid values, where ).

I am attaching the surface before smoothing (1st image), after smoothing with the Poisson solver (2nd image), as well as on its side (3rd image).

As you can see on the side image, the -ve values go all the way to -6.6 something. My question is why, as in the original surface the most negative value is -0.69...

**Why are Dirichlet conditions smoothing the curve down and then up creating troughs? When I use Neumann boundaries of 0 gradient, the troughs disappear, i.e. the surface always slopes down...**

Thank you, any help is appreciated.

Link Copied

1 Reply

Alexander_K_Intel2

Employee

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

01-04-2018
05:37 PM

54 Views

Hi,

It's quite hard to understand the issue based on picture in your post. Can i ask you to send example of your program to check correctness of your boundary condition? And if you solve Poisson equation can i ask the values of rhs?

Thanks,

Alex

Topic Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

For more complete information about compiler optimizations, see our Optimization Notice.