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How to solve ODE y'' - 4y' + y - x = 0 using rk4?

asked 8 years ago

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How to solve ODE y''+y''-4y'+x = 0 using rk4?

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This looks like homework. If you want some help, you should ask more precise questions related to your research in solving those exercises, especially where you are locked.

tmonteil gravatar imagetmonteil ( 8 years ago )

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answered 8 years ago

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

I tryed

 # w = y''
 # z = y'

var('x, w, z')

desolve_system_rk4( [w , 4*z + x] , [w,z] , ics = [0,1,0], ivar = x, end_points = 10, step = 0.1)

But does no work correty :(

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answered 8 years ago

tmonteil gravatar image
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I got a way to solve the differential equation. If wrong please correct;)

To solve this differential equation we must first make a variable substitution to reduce the differential equation for a first order and thus create a system of ODEs. variable change:

w1 = y w2 = y w3 = y '

Thus, deriving the above variables, we have a system of equations of the form:

w1 '= w2 w2 '= f (x, w1, w2) = 4 * w2 + x

desolve_system_rk4([w2, 4*w2 + x ],[w1 , w2], ics = [0,1,0],ivar = x, step = 0.1, end_points = 2)

jmarcellopereira gravatar imagejmarcellopereira ( 8 years ago )

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Asked: 8 years ago

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Last updated: Sep 06 '16