When one encounters a purported solution in the literature, even if one does not derive the solution, one should check it as much as possible. Do this with Eq. (8.88) by verifying that it satisfies the differential equation, the initial condition and the boundary conditions.

Since the organism survives to age t if it has positive vitality at that age, we conclude that

Evidently, Pv(t) will be related to Gaussian cumulative distribution functions, but Anderson chooses to use the error function erf(z) and complementary error function erfc(z) (Abramowitz and Stegun 1974) and since this will give you a new tool, I will do that too (I am also personally very fond of the error function (Mangel and Ludwig 1977)). These functions are defined by erf(z)= — \ p e-2 dt erfc(z) = —= J p e-2 dt

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