An Alternate Solver of ODEs

Besides ‘ode2’, ‘contrib_ode’ also solves differential equations.

For example,

\frac{d^2y}{dx^2} - \frac{1+x}{x} \cdot \frac{dy}{dx}+ \frac{1}{x}\cdot y=0.

While ‘ode2’ fails:

‘contrib_ode’ succeeds:

This is an example taking from page 4 of Bender and Orszag’s “Advanced Mathematical Methods for Scientists and Engineers“. On the same page, there is another good example:

\frac{dy}{dx} = \frac{A^2}{x^4}-y^2, \quad\quad A is a constant.

Using ‘contrib_ode’, we have

It seems that ‘contrib_ode’ is a better differential equation solver than ‘ode2’:

Even though it is not perfect:

From the examples, we see the usage of ‘contrib_ode’ is the same as ‘ode2’. However, unlike ‘ode2’, ‘contrib_ode’ always return a list of solution(s). It means to solve either initial-value or boundary-value problem, the solution of the differential equation is often lifted out of this list first:


Exercise Solve the following differential equations without using a CAS:

  1. \frac{dy}{dx}= \frac{A^2}{x^4} - y^2 (hint: Riccati Equation)
  2. \frac{d^2 y}{dx^2} = \frac{y \frac{dy}{dx}} {x}

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