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Re: DSolve test

Started bySasa B <neprihvatljivo@gmail.com>
First post2014-05-12 04:46 +0000
Last post2014-05-13 02:27 +0000
Articles 2 — 2 participants

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  Re: DSolve test Sasa B <neprihvatljivo@gmail.com> - 2014-05-12 04:46 +0000
    Re: DSolve test carlos.felippa%colorado.edu@gtempaccount.com - 2014-05-13 02:27 +0000

#16939 — Re: DSolve test

FromSasa B <neprihvatljivo@gmail.com>
Date2014-05-12 04:46 +0000
SubjectRe: DSolve test
Message-ID<lkpjmc$lmi$1@smc.vnet.net>
First, all the best to one of the most influential mechanics teacher of our
time, I'm glad to give this minor help :)


Bug doesn't seem fixed

sol = DSolve[{u'[t] == 2*Sqrt[u[t]], u[0] == 0}, u[t], t]; Print[sol];

returns

{{u[t]->t^2}}

(Mathematica 9, Intel 4570)


Aleksandar Borkovic






On Fri, May 9, 2014 at 8:07 AM, <
carlos.felippa%colorado.edu@gtempaccount.com> wrote:

> 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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#16944

Fromcarlos.felippa%colorado.edu@gtempaccount.com
Date2014-05-13 02:27 +0000
Message-ID<lkrvu1$2o$1@smc.vnet.net>
In reply to#16939
On Sunday, May 11, 2014 10:46:04 PM UTC-6, Sasa B wrote:
> First, all the best to one of the most influential mechanics teacher of our
> 
> time, I'm glad to give this minor help :)
> 
> 
> 
> 
> 
> Bug doesn't seem fixed
> 
> 
> 
> sol = DSolve[{u'[t] == 2*Sqrt[u[t]], u[0] == 0}, u[t], t]; Print[sol];
> 
> 
> 
> returns
> 
> 
> 
> {{u[t]->t^2}}
> 
> 
> 
> (Mathematica 9, Intel 4570)
> 
> 
> 
> 
> 
> Aleksandar Borkovic
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> On Fri, May 9, 2014 at 8:07 AM, <
> 
> carlos.felippa%colorado.edu@gtempaccount.com> wrote:
> 
> 
> 
> > 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.
> 
> >
> 
> >

Thanks to all who replied.  The bug is still there :-(

u=t=0 is a fixed branch point. Two solutions: u=0 and u=t^2.
DSolve only returns the latter.

I can give other examples if interested.

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