How I can optimize my code for a stack construct?

2 views (last 30 days)
In reality I have nine variables with scalar values. For them, I have built a stack construct (last in first out) with following logic: push (only for three variabled from nine, as an example)
stack(end+1:end+3) = [value1, value2, value3];
read and pop is
value3 = stack(end); stack = [];
value2 = stack(end); stack = [];
value1 = stack(end); stack = [];
In my script I call these code lines over 8 million time each and that is why I wish the time could be less. Can you help me to optimize the code lines and decrease the speed?

Answers (1)

Rik on 19 Apr 2021
Dynamically growing a variable is generally slow, because Matlab needs to copy the entire array.
You could pre-allocate a stack and use a counter to keep track of the position in the stack.
Rik on 19 Apr 2021
Matlab is copying the array for you: if you add an element to a vector Matlab will allocate a new block of memory, copy all the data (appending your new elements), and free the old memory blocks.
%these two operations are the exact same:
stack(end+1:end+3) = [value1, value2, value3];
stack = [stack, value1, value2, value3];

Sign in to comment.


Find more on Performance and Memory in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!