Depiction of distance measurement by the dynamic time warp algorithm. In the left panels, pulse profiles are shown as query and reference profiles corresponding to the x and y axes of the local cost matrix where the ‘warping path’ is computed. In the right panels, the same two profiles now show a subset of warping tracks highlighting matched samples along the warping path. The top row shows a comparison of a profile from PSR B0950+08 (J0953+0755) with itself leading a path of least resistance (following the heat map ‘cost valley’) corresponding to a perfect diagonal in the local cost matrix. The bottom row shows a comparison of PSR B0950+08 (J0953+0755) as a query with J1803–2137 (B1800–21) as a reference. The path of least resistance steps off the perfect diagonal, leading to a higher distance measure. The heat map also highlights the band of size K = 256 used to constrain our search.