How I can optimize my code for a stack construct?

2 次查看（过去 30 天）
Nazar Adamchuk
Nazar Adamchuk 2021-4-19
评论： Rik 2021-4-19
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?

请先登录，再回答此问题。

回答（1 个）

Rik
Rik 2021-4-19
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.
  2 个评论
Nazar Adamchuk
Nazar Adamchuk 2021-4-19
I am not copying the array, I am appending the elements to the array. That would be copying:
stack = [stack value1 value2 value3]
Rik
Rik 2021-4-19
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];

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Get Started with Optimization Toolbox 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by