Informal Parallel Programming Course for High School Students

1. Informal Parallel Programming Course for High School Students Fall 2007 By: Alex Valentin

2. Who? • Uzi Vishkin, UMD Professor • Scott Watson, UMD Graduate Student • 10 Montgomery Blair Students • Me

3. Why? • Think Differently • Target younger audience • Parallel is the Future

4. What? • Language: XMT-C • Spawn • Ps( ) • Hardware: 64-processor computer

5. HW0: Exchange Problem Swap elements from A[ ] with those of B[ ] Input: A[ ], B[ ], n = length of arrays #include <xmtc.h> int main( ) { int x; for(x=0; x<n; x++){ int e= A[x]; A[x] = B[x]; B[x] = e; }//end for }//end main #include <xmtc.h> int main() { spawn(0,n-1){ Int x ; x= A[$]; A[$] = B[$]; B[$] = x[$]; }//end for }//end main

6. Optimal Parallel Exchange int main() { int y[n]; int x[n]; spawn(0,2*n-1) { if($<n) x[$] = A[$]; else y[$%n] = B[$%n]; } spawn(0, 2*n-1) { if($<n) A[$] = y[$]; else B[$%n] = x[$%n]; } }

7. HW3: Compaction • Given a sparse array, copy all non-zero values into a new array • Input: A[ ], B[ ], C[ ], n= length of arrays • To be done in constant time, O(1)

8. Compaction Code int main(void) { int ptr=0; int l; for(l=0; l<n; l++) { if(B[l] != 0) { C[ptr] = A[l]; ptr++; } }//end for }//end main #include <xmtc.h> psBaseReg base; int main (void) { base =0; spawn(0, n-1) { int step =1; if( B[$] != 0) { ps( step, base); C[step] = A[$]; } }//end spawn }// end main

9. The Future • Ear Decomposition Search ( EDS) • Sub-Graph of Input • Parallel equivalence of Depth-First-Search • st-Numbering