Hi @laura bagnale, you can use the function handle and choose a suitable plot function for representation that best fits your needs
p00 = 0.909722222222223;
p10 = -0.233216488601376;
p01= 0.264523899711384;
p20=-1.06968750000000;
p11=-0.0207056503962889;
p02=0.578645833333333;
q00=0.907638888888890;
q10=0.00799330706899891;
q01=0.0257069830283098;
q20=0.0382031250000013;
q11=0.0414113007925775;
q02=-0.628619791666669;
%using function handle
a = @(x,y)(p20.*q11.*2.0-p11.*q20.*2.0).*x.^2+(p20.*q20.*4.0-p02.*q20.*4.0).*x.*y+(p10.*q11-p01.*q20.*2.0-p11.*q10+p20.*q01.*2.0).*x+(p11.*q20.*2.0-p02.*q11.*2.0).*y.^2+(p11.*q01-p02.*q10.*2.0-p01.*q11+p10.*q20.*2.0).*y+(p10.*q01-p01.*q10)
f = a([-5:5],[-5:5]) % give the range of values for x
% example 1
plot(f)
%example 2
[X,Y] = meshgrid(linspace(-5,5,50),linspace(-5,5,50));
surf(X,Y,a(X,Y))
