function vf = vfield1(t,vec)
% Defines the vector field in computing the bifurcation curves for f=func1
% vf(1) is df/dx, vf(2) is -df/dr
r = vec(1);
x = vec(2);

vf(1) = r*(sech(x))^2 - 1;
vf(2) = -tanh(x);
vf = vf';