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Question: how to move all derivatives to one side of equation?

Question:how to move all derivatives to one side of equation?

nm 8552 Maple 2019
programming differential-equations
August 16 2019
1

To help decide the type of ODE, I need a function which moves all derivatives to lhs and everything else to the rhs of the ODE. This way I can more easily analyze the ODE.

The ode will be only first order. Any term which contains  (y')^n, is to be moved to the lhs. Rest to rhs. Couple of examples will help illustrate the problem. This is done in code only, without looking at the screen. The dependent variable is always y and the independent variable is x.  So I need to turn the ODE to the form 

                    G(y',y'^2,y'^3,.....,y'^n)  = F(x,y)

I can find all derivatives in the ODE using

indets['flat'](ode,{`^`('identical'(diff(y(x),x)),'algebraic'),'identical'(diff(y(x),x))})

But not sure how this will help me do what I want. isolate does not help, since it only takes one term at a time. Collect also did not help for same reason.  If the ODE contains only ONE derivative, then it is easy to do. But the question is about how to do it for ODE which contains more than y' term of different powers as the examples below show.

What methods to do this in Maple? I looked at DEtools but so far did not see anything.

Example 1

 
> 

restart;
ode:=3*diff(y(x),x)^2+diff(y(x),x)^3+sin(x)+y(x)=x*y(x)+x*diff(y(x),x);

3*(diff(y(x), x))^2+(diff(y(x), x))^3+sin(x)+y(x) = x*y(x)+x*(diff(y(x), x))

> 

indets['flat'](ode,{`^`('identical'(diff(y(x),x)),'algebraic'),'identical'(diff(y(x),x))})

{(diff(y(x), x))^2, (diff(y(x), x))^3, diff(y(x), x)}

> 

ode_wanted:= 3*diff(y(x),x)^2+diff(y(x),x)^3-x*diff(y(x),x)=-sin(x)-y(x)+x*y(x)

3*(diff(y(x), x))^2+(diff(y(x), x))^3-x*(diff(y(x), x)) = -sin(x)-y(x)+x*y(x)

Example 2

 
> 

restart;
ode:=3*diff(y(x),x)^2+diff(y(x),x)=x*diff(y(x),x)+5;

3*(diff(y(x), x))^2+diff(y(x), x) = x*(diff(y(x), x))+5

> 

indets['flat'](ode,{`^`('identical'(diff(y(x),x)),'algebraic'),'identical'(diff(y(x),x))})

{(diff(y(x), x))^2, diff(y(x), x)}

> 

ode_wanted:= 3*diff(y(x),x)^2+diff(y(x),x)-x*diff(y(x),x)=5

3*(diff(y(x), x))^2+diff(y(x), x)-x*(diff(y(x), x)) = 5

> 

 

 

Download lhs_rhs.mw

 
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