FX

clear
x = 200*rand(1)-100;
y = 200*rand(1)-100;
dx = 0.1;

for i=1:1000
    sused0 = [x,y];
    sused1 = [x,y-dx];
    sused2 = [x+dx,y];
    sused3 = [x+dx,y+dx];
    sused4 = [x, y+dx];
    sused5 = [x-dx,y+dx];
    sused6 = [x-dx,y];
    sused7 = [x-dx,y-dx];
    sused8 = [x+dx,y-dx];

    sused =[sused0;sused1;sused2;sused3;sused4;sused5;sused6;sused7;sused8];

    S = testfn1(sused);

    [m,indx]=min(S);
    if x==sused(indx,1) && y==sused(indx,2)
        break;

    else
         x=sused(indx,1);
         y=sused(indx,2);

    end
    graf(i) = m;
end
plot(graf)
x
y