The most common problem I see here on Answers is forgetting to use element-wise division, so (./) instead of (/).
Making those two corrections in ‘y1’ and ‘y3’ —
dell=0.5;
n=0.5;
x1= linspace(-0.5,0,100);
y1=-((x1+(dell/2)).^(1/n))./x1;
plot(x1,y1,'-o');
hold on;
x2=0;
y2=0;
plot(x2,y2,'-o');
x3= linspace(0.5,0,100);
y3=((x3-(dell/2)).^(1/n))./x3;
plot(x3,y3,'-o');
hold off;
It may not be the plot you want (I’m not certain what is going on with that), however it’s likely closer.
