Assignment 8 Solution

Description

Question 1 Matrices Multiplication:

1. (5 marks) Given two square matrices A_{n n} and B_{n n}, design a multithreded algorithm (in pseducode) that computes A B with work (n³) but span only (log n).

2. (6 marks) Using your algorithm in (a) as a base, design a multithreaded algorithm that compute A B where A_{p q} and B_{q r} are two given matrices.

3. (6 marks) Analyze both of your algorithms in (a) and (b).

Note: in part (b), your algorithm should be highly parallel even if any of p, q, and r are 1.

Question 2 (a) (5 marks) Given a square matrix A_{n n}, design an e cient multithreaded algorithm that compute A^T (A-transpose) in place by using a divide-and-conquer approach (i.e. dividing the matrix recursively into four (n=2 n=2) submatrices C, D, E, and F .)

A =	C	D	;
	E	F n n

where the dimensions of all C; D; E; and F are (ⁿ₂ ⁿ₂ )

2. (3 marks) Analyze your algorithm in (a).

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