Figure 8:

Illustration of the sampling fashion for non-minimal bandwidth. We consider the curve as shown in (a), which is given by the zero level set of a trigonometric polynomial of bandwidth 5 × 5. We choose the non-minimal bandwidth Γ as 11 × 11. According to the sampling condition for non-minimal bandwidth, we sampled on 72 random locations. We randomly chose two null-space vectors for the feature matrix of the sampling set, which gave us functions (c) and (d). We can see that all of these functions have zeros on the original zero set, in addition to processing several other zeros. The sum of squares function is shown in (e), showing the common zeros, which specifies the original curve.