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(48G 49G 50G) Runge-Kutta Diff Eqn solver
06-15-2021, 09:09 PM
Post: #17
RE: 48G-50G Runge-Kutta Diff Eqn solver
HP Solve doesn't solve DEs numerically. Runge-Kutta integrates along the unknown function trajectory. HP Solve finds roots of expressions. Not the same. I was interested in Vfinal and Sfinal when
V' = 9.8 - 0.005 V^2 m/s^2 for T0 = V0 = 0.0 and Tfinal = 10
Analytically, the integral of dv / ((1 - (0.005 / 9.8 ) V^2), which I don't want to have to look up (like surveying before the HP-35: eight place tables of Sin and Tan, and a Monroe hand-crank calculator). Great that there is a handy calculator function to solve those pesky DEs.

But the utility of the RKF solver is hampered save for Werner's guess that a << program object>> could be substituted for an 'algebraic object/expression', which is undocumented. I really do not think the firmware writers gave this much thought.

Thanks for the link to the pdf of HP-48 Insights.
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RE: 48G-50G Runge-Kutta Diff Eqn solver - rcthacker - 06-15-2021 09:09 PM

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