x=[-1 -0.75 -0.50 -0.25 0 0.25 0.50 0.75 1.00]';
y=[-0.2209 0.3295 0.8826 1.4392 2.0003 2.5645 3.1334 3.7061 4.2836]';
A=polyfit(x,y,2);
plot(x,y,'*');
hold on
x1=-1:0.01:1;
y1=polyval(A,x1);
plot(x1,y1)
x=[-1 -0.75 -0.50 -0.25 0 0.25 0.50 0.75 1.00]';
y=[-0.2209 0.3295 0.8826 1.4392 2.0003 2.5645 3.1334 3.7061 4.2836]';
A=polyfit(x,y,2);
plot(x,y,'*');
hold on
x1=-1:0.01:1;
y1=polyval(A,x1);
plot(x1,y1)