Logical Array Memory Allocation

Why does Matlab allocate one byte for every element in a logical array? Is there a way to make it one bit per element?

Answer 1

[David Young]

There's a trade-off between speed and memory use. Accessing and updating individual bits is slow, due to the underlying hardware architecture. MATLAB goes for a compromise that is good for most cases.

There is no 1-bit data type in MATLAB. If you really need to save memory as a top priority, you can store 8 bits to a byte using bitset and bitget operations on an array of integers.

EDIT 29 Nov 11

An update: I've just remembered bwpack and bwunpack in the Image Processing Toolbox. You could possibly make use of these.

Answer 2

[Jan]

Modern Matlab versions use a byte to store LOGICALs, as most other programming languages do. Storing the single bits is much slower, as David has explained already.

BTW, Matlab 5.3 used DOUBLEs (64 bits!) and set an extra flag to mark the variable as LOGICAL.