Hi, could somebody try this in Mathematica 9 to see if the bug is fixed? sol = DSolve[{u'[t] == 2*Sqrt[u[t]], u[0] == 0}, u[t], t]; Print[sol]; Thanks.

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5/9/2014 6:08:06 AM

Am 09.05.2014 08:08, schrieb carlos.felippa%colorado.edu@gtempaccount.com: > Hi, could somebody try this in Mathematica 9 to see if the bug is fixed? > > sol = DSolve[{u'[t] == 2*Sqrt[u[t]], u[0] == 0}, u[t], t]; Print[sol]; In all versions until now, Mathematica does not check the Lipshitz condition |f(u(t))-f(u(0))| < C |u(t)-u(0)| that guaranties uniqueness. The results for nonlinear ordinary differential equations are just those you find in the usual lists like Kamke oder EquationWorld. There exist no general algebraic nonlinear solving methods for nonlinear ODE's except linear substitutions, separation of variables and lookup tables. Generally as a student of ODE one learns to look for points of discontinuities, here u=0, which generally allow branching: f(t):=0 /;t<=t0 f(t):=(t-t0)^2/; t>t0>=0 is the solution family on (-oo,oo). Dsolve has no entry for a domain construct like NDSolve NDSolve[{u'[t] == 2*Sqrt[u[t]], u[0] == 0}, u[t],{t,0,10}] that will give you the missing constant solution and. But In[20]:= v[t_] = u[t] /. NDSolve[{u'[t] == 2 Sqrt[u[t]], u[1] == 10^-12}, u[t], {t, 0, 7}][[1]] There occurs an error in the internal procedure at the critical point 1: >>During evaluation of In[20]:= NDSolve::mxst: Maximum number of 10000 >>steps reached at the point t == 0.9998803430478553`. So even with CASystems, it is still the fact that differentiation is an algebraic functor, numerical integration is a trivialtity for smooth functions, algebraic integration is a mystery and a historical source of many branches of mathematics. The solution of nonlinear differential equations remains an ingenious kind of art, Ricatti, Clairaut, d'Alembert are some of the protagonists. -- Roland Franzius

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5/14/2014 9:25:37 AM

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My filter is off and I still see no messages in COGM. Testing! Testing! 1-2-3 Testing! Here in comp.os.geos.misc, "Pat" <hotpatpar@hotmail.com> spake unto us, saying: >My filter is off and I still see no messages in COGM. Oh no! :-) -- -Rich Steiner >>>---> http://www.visi.com/~rsteiner >>>---> Smyrna, GA USA OS/2 + eCS + Linux + Win95 + DOS + PC/GEOS + Executor = PC Hobbyist Heaven! WARNING: I've seen FIELDATA FORTRAN V and I know how to use it! The Theorem Theorem: If If, Then Then. Pat w...

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Excuse the ring -- I am confused about the new google "nickname" thing. Dave Weaver Dave Weaver wrote: > Excuse the ring -- I am confused about the new google "nickname" thing. > Dave Weaver Well, that worked just great, using nickname "Dave Weaver" nofinway@fnh.com Dave Weaver wrote: > Excuse the ring -- I am confused about the new google "nickname" > thing. Dave Weaver Dave, I hope you realize that by posting via Google Groups, your e-mail address will be made public to Usenet groups. Tiny URL http://tinyur...

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Yup. Another test. - -- Douglas J. Renze drenze [at] earthlink [dot] net -----BEGIN PGP SIGNATURE----- iD8DBQFFHEp7lGygHPhROTwRAsPuAJ49WaSpUh3Ffs1hBsc6QBtxCPB88QCfTCCc 5DYApr0CMfcV3sQYm1tJdLY= =lzI0 -----END PGP SIGNATURE----- Douglas J. Renze wrote: > Yup. Another test. > UNTRUSTED Good signature from Douglas J. Renze <MUNGED> Key ID: 0xF851393C / Signed on: 09/28/2006 05:19 PM Key fingerprint: A165 18AE 7607 5549 8C64 59FB 946C A01C F851 393C ...

Test test werty wrote: > Test test > You failed, horribly. Please return your computer to where you bought it and tell them they don't need to refund the money, because you're too stupid to know the difference anyway. Stop such nonsense. Google said they turned it off 9 Jan . They changed dates on posts , then put them in , 10 Jan . I did not post 9 Jan If they would only tell the truth ..... Its called throttling . Google dont want to pay to carry UseNet ... but they like the revenues from adverts . ...

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TEST TEST TEST 222222222222 NikVi <VVNikitin@yandex.ru> wrote: > TEST TEST TEST 222222222222 Your test failed. With over 1000 newgroups .test your post showed up here. Now go read the FAQ and some other documentation before posting. Davide -- | Simon's Law: Everything put together falls apart sooner or later. | | | ...

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Test test werty <werty@swissinfo.org> wrote: > Test test THERE ARE TEST GROUPS FOR TESTING - USE THEM please :-) Jim ...

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