how can i find the the equation between two variables from their graph

if A & B are two arrays of a given data.after ploting it and curve fitting ( A=[2 4 6]; B=[1 2 3]; d=plot(A,B)) how can i retrieve the differential equation between A & B? let the equation is second order

[manoj saini]

TRY THE CODE polyfit(A,B,2)

Answer 1

[Matt J]

Perhaps with the System Identification Toolbox