Accelerating MATLAB Performance

140 Accelerating MATLAB

®

Performance

than true-color RGB images (e.g., PNG) for at-color cartoons.* However, while no space

is allocated for unused indexes, space is indeed allocated for all possible column indexes

as a global overhead. For this reason, it is generally better to reshape the data such that

the large dimension is stored as the sparse-data row rather than the column (i.e., ensure a

smaller column dimension):

360

s1 = sparse([],[],[],1,N); % row vector - slower, more memory

⇨ Elapsed time is 0.023915 seconds.

s2 = sparse([],[],[],N,1); % column vector - much faster, low memory

⇨ Elapsed time is 0.000031 seconds.

>> whos s1 s2 ...