Profile width evolution of PSR J0738–4042. The figure on the left shows the stack of normalized profiles, with the profile peak placed at 180° for each subband. (Middle) The profile width has been measured at varying intensity levels, shown from dark to light colors, in relation to frequency. The dashed lines represent the best-fit solutions of Eq. (1). The resulting parameters as a function of profile intensity level are shown in the right panel. The black, blue, and red lines respectively represent the amplitude, A; the power index, μ; and the y-offset, W₀.