Figure 1From: The black hole accretion code Modified Kerr-Schild coordinates. θ-grid stretching functions comparing the transcendental function \(\vartheta(\theta_{\mathrm{KS}})\) (solid red curves) with the cubic approach (solid blue curves) for \(h=0.9\). We also give the respective derivatives \(d\theta/d\vartheta\) (dashed).Back to article page