Optimization_4x4_9

Copy the contents of file MMult_4x4_8.c into a file named MMult_4x4_9.c and change the contents.

Change the first lines in the makefile to

OLD  := MMult_4x4_8
NEW  := MMult_4x4_9

• make run

octave:3> PlotAll        % this will create the plot

This time the performance graph will look something like

From 4x4_8 to 4x4_9 is a subtle change: instead of updating the rows of 4x4 block C a row at a time, we compute them two rows at a time. This sets us up for using vector operations, where we update pairs C( 0,j ) and C( 1,j ) (j =0,...,3) with vector operations.