Persistent variable buffer size

I need to make a persistent variable that can take maximum x scalars. After x is reached the oldest scalar stored gets out and the new one gets in (FIFO).

How can I define such variable?

Answer 1

[Jan]

What have you tried and which problems occur?

function YourFcn(Value)

% Initialize the buffer on demand:
persistent Buffer BufferIndex
MaxBufferLen = 19;
if isempty(BufferIndex)  % First run
  BufferIndex = 1;
  % Pre-allocation if possible: Buffer = nan(1, MaxBufferLen)
end

% Store the current value:
Buffer(BufferIndex) = Value;

% Increase and restart the index:
BufferIndex = mod(BufferIndex, MaxBufferLen) + 1