Power series solution of differential equations calculator wolfram

Power series solution of differential equations calculator wolfram

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Power series solution of differential equations calculator wolfram

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Power series solution of differential equations calculator wolfram

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Examples

  • separable\:y'=e^{-y}(2x-4)
  • separable\:\frac{dr}{d\theta}=\frac{r^2}{\theta}
  • separable\:y'=\frac{xy^3}{\sqrt{1+x^2}}
  • separable\:y'=\frac{xy^3}{\sqrt{1+x^2}},\:y(0)=-1
  • separable\:y'=\frac{3x^2+4x-4}{2y-4},\:y(1)=3

separable-differential-equation-calculator

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Compute the formula for the Frobenius series solution to an ODE

Contributed by: Rauan Kaldybayev

ResourceFunction["FrobeniusDSolveFormula"][eqn,u,x,x0]

outputs a formula to be fed into the resource function FrobeniusDSolve.

ResourceFunction["FrobeniusDSolveFormula"][eqn,u,x,x0,Association]

outputs the formula for the Frobenius series solution

Power series solution of differential equations calculator wolfram
of a differential equation for the function u, with independent variable x.

Details and Options

The output is a formula describing a Frobenius series

Power series solution of differential equations calculator wolfram
. It is a list of the form {elem1,elem2,}, where the elemi gives information about the ith solution.

Solving ODEs using Frobenius's method is a tedious monotonous work, yet it is very simple - a perfect process to automate. ResourceFunction["FrobeniusDSolveFormula"] can be used to compute a formula for the Frobenius series solution to an ODE

Power series solution of differential equations calculator wolfram
. Computing a Frobenius series solution by hand can lead to potential insights or be helpful in conceptually understanding the behavior of the solutions.

Another application for ResourceFunction["FrobeniusDSolveFormula"] is to assist the resource function FrobeniusDSolve. When solving an ODE, FrobeniusDSolve first utilizes ResourceFunction["FrobeniusDSolveFormula"] to compute a formula for the solution. The formula is then used to calculate the approximate solutions. When a single ODE is to be solved many times with different parameters, computation time can be significantly reduced by computing the formula separately, using ResourceFunction["FrobeniusDSolveFormula"]. (see Applications)

The function can be used to solve linear homogeneous ODEs with polynomial coefficients.

Any linear ODE with polynomial coefficients can be written in the form

Power series solution of differential equations calculator wolfram
for some (any) x0. Frobenius's method assumes solution of the form
Power series solution of differential equations calculator wolfram
; substituting this into the equation yields
Power series solution of differential equations calculator wolfram
, where
Power series solution of differential equations calculator wolfram
. To satisfy the equation, the coefficients before all powers of x-x0 must be zero for all k. From here, we can determine the possible values of the constant r for which a00, and then for each r, compute the coefficients. Read more at the related Wolfram Community post.

The options for ResourceFunction["FrobeniusDSolveFormula"] are:

"ComputeError" False whether to compute the error of the approximate solution

Examples

  • Open in Cloud
  • Download Notebook

Basic Examples (2) 

Obtain a formula for the Frobenius solution for the ODE 2x2y''+7x(x+1)y'-3y=0 near the singular point x=0:

In[1]:=

Power series solution of differential equations calculator wolfram

Out[1]=

Power series solution of differential equations calculator wolfram

The formula describes a Frobenius series

Power series solution of differential equations calculator wolfram
. Display the same formula in a form compatible with the resource function FrobeniusDSolve (see Properties and Relations):

In[2]:=

Power series solution of differential equations calculator wolfram

Out[2]=

Power series solution of differential equations calculator wolfram

Scope (3) 

The function can operate with complex numbers:

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Power series solution of differential equations calculator wolfram

Out[3]=

Power series solution of differential equations calculator wolfram


The inputs of the function can be symbolics:

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Power series solution of differential equations calculator wolfram

Out[4]=

Power series solution of differential equations calculator wolfram


FrobeniusDSolveFormula can be used to solve ODEs of any order. Here is the formula for the Frobenius series solution to (x-1)4f''''[x]=x(2+x)f[x]+x2(x-1)2f''[x]-19(x-1)3f'''[x] near the singular point x=1:

In[5]:=

Power series solution of differential equations calculator wolfram

Out[5]=

Power series solution of differential equations calculator wolfram

Options (1) 

If the option "ComputeError" is set to True, FrobeniusDSolveFormula will not only output a formula for the Frobenius series solution but also the formula for the error of this solution:

In[6]:=

Power series solution of differential equations calculator wolfram

Out[6]=

Power series solution of differential equations calculator wolfram

The formula doesn't make much sense to a human and instead is meant to be fed into the resource function FrobeniusDSolve, which will in turn compute an approximate solution of the form

Power series solution of differential equations calculator wolfram
and the error of this solution.

Applications (2) 

FrobeniusDSolve is a related resource function that computes approximate Frobenius and power series solutions to ODEs. The solutions it outputs are of the form

Power series solution of differential equations calculator wolfram
for some parameters x0, j. The following is an example of how FrobeniusDSolve can be used to obtain approximate solutions to the ODE x2y''-2xy'+(1+x)y=0 with x0=0 and n=4:

In[7]:=

Power series solution of differential equations calculator wolfram

Out[7]=

Power series solution of differential equations calculator wolfram

When solving an ODE, FrobeniusDSolve first utilizes FrobeniusDSolveFormula to compute a formula for the solution. The formula is then used to calculate the approximate solutions. When a single ODE is to be solved many times with different parameters, computation time can be significantly reduced by computing the formula separately, using FrobeniusDSolveFormula. This way, FrobeniusDSolve doesn't have to compute the formula every time, and it only has to do the numerical part of the computation. As can be seen from the following example, the decrease in computation time is dramatic:

In[8]:=

Power series solution of differential equations calculator wolfram

Out[9]=

Power series solution of differential equations calculator wolfram

Properties and Relations (2) 

Formulas given by FrobeniusDSolveFormula can be fed into the resource function FrobeniusDSolve to compute approximate Frobenius series solutions. This can help significantly improve efficiency when a single ODE is to be solved repeatedly (see Applications). Obtain a formula for the Frobenius solution for the ODE 2x2y''+7x(x+1)y'-3y=0 near the singular point x=0, and output it in a form compatible with FrobeniusDSolve:

In[10]:=

Power series solution of differential equations calculator wolfram

Out[10]=

Power series solution of differential equations calculator wolfram

Use the formula to compute two linearly independent approximate solutions

Power series solution of differential equations calculator wolfram
:

In[11]:=

Power series solution of differential equations calculator wolfram

Out[11]=

Power series solution of differential equations calculator wolfram

In[12]:=

Power series solution of differential equations calculator wolfram

Out[12]=

Power series solution of differential equations calculator wolfram

Possible Issues (2) 

The ODE must be linear and homogeneous, and its coefficients must be polynomial. Otherwise, FrobeniusDSolveFormula returns $Failed:

In[13]:=

Power series solution of differential equations calculator wolfram

Out[13]=

Power series solution of differential equations calculator wolfram

In[14]:=

Power series solution of differential equations calculator wolfram

Out[14]=

Power series solution of differential equations calculator wolfram

In[15]:=

Power series solution of differential equations calculator wolfram

Out[15]=

Power series solution of differential equations calculator wolfram


If the ODE isn't liner but can be made so by dividing by a non-zero factor, the function still doesn't accept it:

In[16]:=

Power series solution of differential equations calculator wolfram

Out[16]=

Power series solution of differential equations calculator wolfram

Publisher

Wolfram Summer Camp

  • http://www.its.caltech.edu/~esp/acm95b/frobenius.pdf

Version History

  • 1.0.0 – 13 April 2021

How do you solve a differential equation with a power series?

Problem-Solving Strategy: Finding Power Series Solutions to Differential Equations.
Assume the differential equation has a solution of the form y(x)=∞∑n=0anxn..
Differentiate the power series term by term to get y′(x)=∞∑n=1nanxn−1. ... .
Substitute the power series expressions into the differential equation..

Can Wolfram Alpha solve system of differential equations?

The Wolfram Language's differential equation solving functions can be applied to many different classes of differential equations, automatically selecting the appropriate algorithms without needing preprocessing by the user.

Why we use power series solution of differential equations?

In mathematics, the power series method is used to seek a power series solution to certain differential equations. In general, such a solution assumes a power series with unknown coefficients, then substitutes that solution into the differential equation to find a recurrence relation for the coefficients.

What is meant by power series solution?

Definition. A power series solution to a differential equation is a function with infinitely many terms, each term containing a different power of the dependent variable. The general solution has the form y = a 0 + a 1 x + a 2 x 2 + a 3 x 3 + ⋯ {\displaystyle y=a_{0}+a_{1}x+a_{2}x^{2}+a_{3}x^{3}+\cdots } .