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--- gibson:teaching:spring-2016:math445:lab5 [2016/02/16 12:00]
vining
+++ gibson:teaching:spring-2016:math445:lab5 [2016/02/18 08:36] (current)
gibson
@@ Line 75: / Line 75: @@
 Write a function ''matvecmult'' that takes a matrix $A$ and a vector $x$ as inputs, computes $y = Ax$ according to that formula, and returns the vector $y$. Compare your ''matvecmult'' to Matlab's built-in matrix-vector multiplication operator ''*'' on a random $4 \times 4$ matrix and a random 4d column vector.
-...to be continued...
+----
+**Problem 7:** The formula for matrix-matrix multiplication $C = AB$ of an $m \times n$ matrix $A$ and an, $n \times p$ matrix $B$ is
+<latex>
+C_{i,j} = \sum_{k=1}^n A_{ik} B_{k,j} \quad \text{ for } i = 1,\dots,m, \text{ and } j = 1,\dots,p,
+</latex>
+The product $C = AB$ is an $m \times p$ matrix.
+Write a function ''matmatmult'' that takes a matrix $A$ and a vector $x$ as inputs, computes $C = AB$ according to that formula, and returns the matrix $C$. Compare your ''matmatmult'' to Matlab's built-in matrix-vector multiplication operator ''*'' on a random $4 \times 3$ matrix $A$ and a random $3 \times 5$ matrix B.