Figure 6.

Absolute numerical error of the CZT–ICZT procedure for chirp contours with 1024 points on the unit circle. The results in (a) are for 3600 regularly-spaced angles with a discretization step of 0.1°. This discretization hits many Farey angles of lower orders, which leads to the layering of the numerical error function. See also Supplementary Fig. S3. The results in (b) are for 3600 polar angles that were randomly sampled from a uniform distribution. The random sampling is less likely to hit Farey angles, which explains the absence of the layering effect seen in (a).