matlab - Contour plot showing no result -

i wondering have following code:

[r,r] = meshgrid(2:0.01:10,-4:0.01:4); z=(((r).^2)-1 );    a=2+ (r.*(r+r^-1));    b=sqrt(z).*(r-r^-1);    c=((r+r^-1)./(sqrt(z))).*acoth(a./b);     figure contourf(r,r,c);     h=colorbar;     set(get(h,'ylabel'),'string','\gamma p_p l')     xlabel('$r$','interpreter','latex','fontsize',18)     ylabel('$d \over 2\sqrt{m}$','interpreter','latex','fontsize',18) 

i , b answers infinite not sure why?

you forgot dot. r^-1 same inv(r). , since of r's rows same first, it's reduced-row echelon form have zeros, , inverse have infinite values. believe meant

a=2+ (r.*(r+r.^-1)); 

or, more in opinion,

a=2+ (r.*(r+ 1./r)); 

and on rest of r^-1.