# finding boundary conditions when transforming a higher order ode to system of first order ode

given the following ODE:

$$\frac{d^{4}w}{dx^{4}} + B\frac{d^{2}w}{dx^{2}} = 1$$

with boundary conditions $$w(0) =0 , w(1) = 0,w'(0) = 0,w'(1) = 0$$

its possible to solve analytically but I am attempting to solve it numerically so I can plot and see how the graph changes as I vary the parameter $$B$$.

in order to solve it numerically i transformed the ODE into a system of first order ODE and i obtained this system:

$$w_{1}' = w_{2}$$

$$w_{2}' = w_{3}$$

$$w_{3}' = w_{4}$$

$$w_{4}' = 1 - B \cdot w_{3}$$

where $$w_{1} = w, w_{2} = w',w_{3} = w'',w_{4} = w'''$$

given those boundary conditions is there a way to determine calculate the boundary conditions for $$w_{3}$$ and $$w_{4}$$ so that can can solve the system numerically?

• Your original problem isn't an initial value problem becomes of the conditions at times t=0 and t=1. Rather, it's a boundary value problem. Thus you can't solve the problem with an IVP solver. Mar 23 at 17:22
• so in order to solve i need to find w1,w2,w3,w4 for t=0 and t=1? Mar 23 at 17:36
• No, four is the correct number of conditions, but you need to be using a method that can solve boundary value problems rather than initial value problems. Mar 23 at 17:44
• @BrianBorchers do you have any material I could use to solve this? specifically in python Mar 23 at 17:51
• You can use initial value solvers via a shooting method. Just need to formulate it that way. Mar 23 at 19:09