Validation of the deterministic forward model in Eq. (4) made by computing the contrast from the same segmented WFE maps with the experimental PASTIS matrix as in the middle panel of Fig. 6 (solid blue), with the simulated PASTIS matrix from the right panel of Fig. 6 (solid green), and with the HiCAT testbed (dashed orange). The curves flatten out to the left at the coronagraph floor, c₀, and show linear behavior at increasing WFE, giving them their hockey-stick-like shape. The contrast calculation from the PASTIS equation with both matrices shows very good accordance with the testbed measurements; all three lines overlap at WFEs larger than 1 nm rms.