How to create a buffer

How to create a buffer for my (X,P,Y,U) i have created arrays of them(Pbuff,Xbuff,Ybuff,Zbuff) now i need to create a buffer using these arrays

Matlab Code : -

% input vector from proprioceptive sensors

deltaq = [ qR(i) - qR(i-1) ;

qL(i) - qL(i-1) ] ;

U = jointToCartesian * deltaq ; % joint speed to Cartesian speed.

Ubuff = numel(U);

X = EvolutionModel( X , U ) ;

Xbuff = numel(X);

P = A*P*(A.') + B*Qbeta*(B.') + Qalpha ;

Pbuff = numel(P);

% Measurement vector: coordinates of the magnet in Rm.

Y = [ sensorPosAlongXm ;

sensorRes*( measures(measNumber) - sensorOffset ) ] ;

Ybuff = numel(Y);