deTaylor
05-22-2015, 08:27 PM
Post: #3
 fhub Member Posts: 191 Joined: Dec 2013
RE: deTaylor
(05-22-2015 06:10 PM)salvomic Wrote:  thank you!

please help to control with an differential equation still not solvable in Prime (but now ok in XCas):
y'=(x+y)^2
Is it correct to input
deTaylor((x+y)^2, [x,y], [0,0], 7) ?

I get (17/315)x^7+(2/15)x^5+(⅓)x^3
The general solution of equation (XCas) is TAN(x-c)-x
With Taylor I've taylor(TAN(x)-x), x, 6) = (⅓)x^3+(2/15)x^5+x^7+o(x)
It should be ok, isn't it?
Not exactly, you should enter order 7 (not 6), then you get the same result as with deTaylor (despite of the error term "x^8*order_size(x)"):

taylor(tan(x)-x), x=0, 7)

Franz
 « Next Oldest | Next Newest »

 Messages In This Thread deTaylor - fhub - 05-22-2015, 01:24 PM RE: deTaylor - salvomic - 05-22-2015, 06:10 PM RE: deTaylor - fhub - 05-22-2015 08:27 PM RE: deTaylor - salvomic - 05-22-2015, 08:31 PM RE: deTaylor - fhub - 05-22-2015, 09:44 PM RE: deTaylor - salvomic - 05-22-2015, 10:13 PM

User(s) browsing this thread: 1 Guest(s)