Comparison between the auto-correlation s (for i = j) calculated in this work and those obtained with the UCLCL code at three BINGO redshift bins, centered at the frequencies 985, 1105, and 1225 MHz (redshifts z ≈ 0.44, 0.28, and 0.16, respectively), and bandwidths of 10 MHz. The upper panel shows the UCLCL results overplotted as dotted lines on each of the calculated curves (colored lines), while the lower panel shows the percentage relative difference among them.