# PAR Homework 5

Hand in your solution on RPILMS, unless instructions say otherwise. Each team should submit its solution under only 1 student's name. The other student's submission should just name the lead student. (This makes it easier for us to avoid grading it twice.)

If you have problems, then ask for help. The goal is to learn the material.

## Homework 5, due Fri 2017-03-10, 9am.

- Rewrite the potential energy problem to be more efficient:
- Impose a 100x100x100 grid on the data.
- Sort the points into the 1M cells.
- For each point:
- Compute the potential of it against all the points in its cell and the 26 (or fewer) neighboring cells.
- For farther cells, aggregate the points in each cell and represent them as one heavy point at the cell center.

- Implement this 3 times, using:
- OpenMP,
- CUDA,
- Thrust.

- Report the times, on the bunny and blade, and on a new point set in /parallel-class/data/unc . It's 5423053 points from a powerplant, from UNC. The points are very unevenly spaced.
- Report how different your answers are for the 3 implementation. Explain any differences.
- Report the time and accuracy of this method compared to your original, brute force, method.

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