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Newbie

help solving a differential equation

Could anyone tell me how to solve the following differential equation:

y*d2y = constant
dx2

many thanks
4 REPLIES 4
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help solving a differential equation

You can easily solve this numerically in Mathcad 2000 using the Odesolve block (see the Resource Center/Overview and Tutorials/Solving Differential Equations). In earlier versions of Mathcad, use rkfixed or any of its cousins.

You can also solve this symbolically by hand by letting p=dy/dx, then d^2y/dx^2=dp/dx=(dp/dy)*(dy/dx)=p*dp/dy by the Chain Rule. So your ode becomes p*dp/dy=a/y, which integrates to p^2/2=a*ln(y)+b. Now replace p by dy/dx and integrate one more time.

Bonnie
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help solving a differential equation

thanks for the reply - is there any chance you could send the file in Mathcad 8 (pro)format?

Thanks again
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