Figure 1From: An attractive numerical algorithm for solving nonlinear Caputo–Fabrizio fractional Abel differential equation in a Hilbert spaceFractional level curves of CF-derivative of Example 5.1: blue \(\alpha = 0.8\), yellow \(\alpha = 0.85\), green \(\alpha = 0.9\), red \(\alpha = 0.95\), and black \(\alpha =1\)Back to article page