@oneofvalts Welp FriCAS uses a somewhat awkward mechanism for ODE, that the function symbol needs to be constructed differently. I took the result as an equation meaning XXX = 0 and try solve it and it turns out the result should be correct.
For example, FriCAS appears to give a wrong answer for this.
@loke The highlighted part is the full implicit solution to the differential equation dP/dt = P(a-b*ln(P)) with initial condition P(0)=c, the next part solves the result to equation P = e^((ln c-a/b)*e^(-bt)-a/b) with some conditions. The result is known as the Gompertz Differential Equation, see https://math.stackexchange.com/questions/2450994/solution-to-gompertz-differential-equation
Made the 3270 Type1 font for plainTeX. Not sure if anyone else would need that because they can just use XeLaTeX with unicode and OTF support.
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