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Question: how to use odetest to very series solution with expansion point at infinity?

Question:how to use odetest to very series solution with expansion point at infinity?

nm 9899 Maple 2022
ode dsolve series differential-equations odetest
June 29 2022
2

I do not remember now if this was asked before. Doing search here is hard. 

But I am trying this now on 2022.1 and this gives FAIL.

What is the correct syntax to use odetest to verify solution to ode using series method with expansion around infinity? Why do I get FAIL here?
 

> 

interface(version)

`Standard Worksheet Interface, Maple 2022.1, Windows 10, May 26 2022 Build ID 1619613`

> 

Physics:-Version()

`The "Physics Updates" version in the MapleCloud is 1257 and is the same as the version installed in this computer, created 2022, June 22, 16:27 hours Pacific Time.`

> 

restart;
> 

ode:=x^3*diff(y(x),x$2)+x^2*diff(y(x),x)+y(x)=0;
sol:=dsolve(ode,y(x),'series',x=infinity);
odetest(sol,ode,'series','point'=infinity)

x^3*(diff(diff(y(x), x), x))+x^2*(diff(y(x), x))+y(x) = 0

y(x) = _C1*(1-1/x+(1/4)/x^2-(1/36)/x^3+(1/576)/x^4-(1/14400)/x^5+O(1/x^6))+_C2*(ln(1/x)*(1-1/x+(1/4)/x^2-(1/36)/x^3+(1/576)/x^4-(1/14400)/x^5+O(1/x^6))+2/x-(3/4)/x^2+(11/108)/x^3-(25/3456)/x^4+(137/432000)/x^5+O(1/x^6))

Warning, unable to compute series necessary to test the given solution

FAIL

> 

 


 

Download odetest_series.mw

Update

I've testsed methods given below on 6 random ode's using Maple odetest, VV method and Axel method. THis is the result obtained using Maple 2022.1 

odetest was able to verify the solution zero out of 6 times.
VV method was able to verify the solution 3 out of 6 times.
Axel method was able to verify the solution 5 out of 6 times.

So based on this small test, Axel method seems to do the best. Attached worksheet. I will use this method to verify my series solution to ode's instead of Maple's odetest but will use Maple's odetest for non-series method solutions.


 

> 

interface(version);

`Standard Worksheet Interface, Maple 2022.1, Windows 10, May 26 2022 Build ID 1619613`

> 

Physics:-Version();

`The "Physics Updates" version in the MapleCloud is 1257 and is the same as the version installed in this computer, created 2022, June 22, 16:27 hours Pacific Time.`

> 

restart;

Example 1  Regular singular point. Complex roots

 
> 

Order:=6;
ode:=sin(x)*diff(y(x),x$2)+cos(x)*diff(y(x),x)+1/x*y(x)=0;
sol:=dsolve(ode,y(x),type='series',x=0)

6

sin(x)*(diff(diff(y(x), x), x))+cos(x)*(diff(y(x), x))+y(x)/x = 0

y(x) = _C1*x^(-I)*(series(1+(1/48-(1/16)*I)*x^2+(1/57600-(217/57600)*I)*x^4+O(x^6),x,6))+_C2*x^I*(series(1+(1/48+(1/16)*I)*x^2+(1/57600+(217/57600)*I)*x^4+O(x^6),x,6))

VV method

 
> 

odetest(sol,ode):
asympt(%,x);

Error, (in asympt) unable to compute series

odetest method

 
> 

odetest(sol,ode,'series','point'=0);

y(x) = _C1*x^(-I)*(series(1+(1/48-(1/16)*I)*x^2+(1/57600-(217/57600)*I)*x^4+O(x^6),x,6))+_C2*x^I*(series(1+(1/48+(1/16)*I)*x^2+(1/57600+(217/57600)*I)*x^4+O(x^6),x,6))

y(t) = _C1*t^(-I)*(series(1+(1/48-(1/16)*I)*t^2+(1/57600-(217/57600)*I)*t^4+O(t^6),t,6))+_C2*t^I*(series(1+(1/48+(1/16)*I)*t^2+(1/57600+(217/57600)*I)*t^4+O(t^6),t,6))

Axel method

 
> 

rhs(sol):
Y:= unapply(%, x):
eval(lhs(ode), y=Y):
MultiSeries:-asympt(%, x):
convert(%,polynom);

0

Example 2 Regular singular point. Difference is integer

 
> 

Order:=6;
ode:=sin(x)*diff(y(x),x$2)+cos(x)*y(x)=0;
sol:=dsolve(ode,y(x),type='series',x=0):

6

sin(x)*(diff(diff(y(x), x), x))+cos(x)*y(x) = 0

VV method

 
> 

odetest(sol,ode):
asympt(%,x);
convert(%,polynom);

O(x^7)

0

odetest method

 
> 

odetest(sol,ode,'series','point'=0);

Warning, unable to compute series necessary to test the given solution

FAIL

y(t) = _C1*t^(-I)*(series(1+(1/48-(1/16)*I)*t^2+(1/57600-(217/57600)*I)*t^4+O(t^6),t,6))+_C2*t^I*(series(1+(1/48+(1/16)*I)*t^2+(1/57600+(217/57600)*I)*t^4+O(t^6),t,6))

Axel method

   
> 

rhs(sol):
Y:= unapply(%, x):
eval(lhs(ode), y=Y):
MultiSeries:-asympt(%, x):
convert(%,polynom);

0

Example 3 Regular singular point. Repeated root

 
> 

Order:=6;
ode:=(exp(x)-1)*diff(y(x),x$2)+exp(x)*diff(y(x),x)+y(x)=0;
sol:=dsolve(ode,y(x),type='series',x=0):

6

(exp(x)-1)*(diff(diff(y(x), x), x))+exp(x)*(diff(y(x), x))+y(x) = 0

VV method

 
> 

odetest(sol,ode):
asympt(%,x):
convert(%,polynom);

0

odetest method

 
> 

odetest(sol,ode,'series','point'=0);

Warning, unable to compute series necessary to test the given solution

FAIL

y(t) = _C1*t^(-I)*(series(1+(1/48-(1/16)*I)*t^2+(1/57600-(217/57600)*I)*t^4+O(t^6),t,6))+_C2*t^I*(series(1+(1/48+(1/16)*I)*t^2+(1/57600+(217/57600)*I)*t^4+O(t^6),t,6))

Axel method

   
> 

rhs(sol):
Y:= unapply(%, x):
eval(lhs(ode), y=Y):
MultiSeries:-asympt(%, x):
convert(%,polynom);

0

Example 4 Regular singular point. Repeated root

 
> 

Order:=6;  
ode:=(exp(x)-1)*diff(y(x),x$2)+exp(x)*diff(y(x),x)+y(x)=0;
sol:=dsolve(ode,y(x),type='series',x=0):

6

(exp(x)-1)*(diff(diff(y(x), x), x))+exp(x)*(diff(y(x), x))+y(x) = 0

VV method

 
> 

odetest(sol,ode):
asympt(%,x):
convert(%,polynom);

0

odetest method

 
> 

odetest(sol,ode,'series','point'=0);

Warning, unable to compute series necessary to test the given solution

FAIL

y(t) = _C1*t^(-I)*(series(1+(1/48-(1/16)*I)*t^2+(1/57600-(217/57600)*I)*t^4+O(t^6),t,6))+_C2*t^I*(series(1+(1/48+(1/16)*I)*t^2+(1/57600+(217/57600)*I)*t^4+O(t^6),t,6))

Axel method

   
> 

rhs(sol):
Y:= unapply(%, x):
eval(lhs(ode), y=Y):
MultiSeries:-asympt(%, x):
convert(%,polynom);

0

Example 5 . Regular singular point. Complex roots

 
> 

Order:=6;  
ode:=x^3*diff(y(x),x$2)+sin(x^3)*diff(y(x),x)+x*y(x)=0;
sol:=dsolve(ode,y(x),type='series',x=0):

6

x^3*(diff(diff(y(x), x), x))+sin(x^3)*(diff(y(x), x))+x*y(x) = 0

VV method

 
> 

odetest(sol,ode):
asympt(%,x);
#convert(%,polynom);

Error, (in asympt) unable to compute series

odetest method

 
> 

odetest(sol,ode,'series','point'=0);

Error, (in odetest/series) need to determine the sign of I*3^(1/2)

y(t) = _C1*t^(-I)*(series(1+(1/48-(1/16)*I)*t^2+(1/57600-(217/57600)*I)*t^4+O(t^6),t,6))+_C2*t^I*(series(1+(1/48+(1/16)*I)*t^2+(1/57600+(217/57600)*I)*t^4+O(t^6),t,6))

Axel method

   
> 

rhs(sol):
Y:= unapply(%, x):
eval(lhs(ode), y=Y):
MultiSeries:-asympt(%, x):
#convert(%,polynom);

Error, (in MultiSeries:-multiseries) need to determine the sign of -I*3^(1/2)

Example 6 . Regular singular point. Complex roots

 
> 

Order:=6;  
ode:=x^2*diff(y(x),x$2)+x*diff(y(x),x)+(x+1)*y(x)=0;
sol:=dsolve(ode,y(x),type='series',x=0):

6

x^2*(diff(diff(y(x), x), x))+x*(diff(y(x), x))+(x+1)*y(x) = 0

VV method

 
> 

odetest(sol,ode):
asympt(%,x);
#convert(%,polynom);

Error, (in asympt) unable to compute series

odetest method

 
> 

odetest(sol,ode,'series','point'=0);

y(x) = _C1*x^(-I)*(series(1+(-1/5-(2/5)*I)*x+(-1/40+(3/40)*I)*x^2+(3/520-(7/1560)*I)*x^3+(-1/2496+(1/12480)*I)*x^4+(9/603200+(1/361920)*I)*x^5+O(x^6),x,6))+_C2*x^I*(series(1+(-1/5+(2/5)*I)*x+(-1/40-(3/40)*I)*x^2+(3/520+(7/1560)*I)*x^3+(-1/2496-(1/12480)*I)*x^4+(9/603200-(1/361920)*I)*x^5+O(x^6),x,6))

y(t) = _C1*t^(-I)*(series(1+(1/48-(1/16)*I)*t^2+(1/57600-(217/57600)*I)*t^4+O(t^6),t,6))+_C2*t^I*(series(1+(1/48+(1/16)*I)*t^2+(1/57600+(217/57600)*I)*t^4+O(t^6),t,6))

Axel method

   
> 

rhs(sol):
Y:= unapply(%, x):
eval(lhs(ode), y=Y):
MultiSeries:-asympt(%, x):
convert(%,polynom);

0

> 

 

> 

 


 

Download test_new_odetest.mw

 

 

 
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