Re: Math 3.0 running but 4.0 little problem.
- To: mathgroup at smc.vnet.net
- Subject: [mg36010] Re: [mg35993] Math 3.0 running but 4.0 little problem.
- From: Vladimir Bondarenko <vvb at mail.strace.net>
- Date: Mon, 12 Aug 2002 03:34:27 -0400 (EDT)
- Reply-to: Vladimir Bondarenko <vvb at mail.strace.net>
- Sender: owner-wri-mathgroup at wolfram.com
SÊrgio Milo <milo at dmo.fee.unicamp.br> wrote on Sun, 11 Aug 2002 05:13:54
SM> In Mathematica 3.0 resolve this equation without problem.
Sure not.
Mathematica 3.0 returns exactly the same warning messages as
Mathematica 4.0 does.
Mathematica got stymied because to get to a sensible output
you must
1) use, in NDSolve, not {x, 0, Z} but something like {x, 0, 1}
so Mathematica's algorithms could "know" over which range
they must work and calculate the stepsize(s) required
2) define coefac[x], alfaam, alfaem, etas, sinalfinal in terms
of constants and/or functions of x and/or y[x] to get
Mathematica the opportunity to plunge into numeric values
How could you recognize your own bug? Just pay attention to
those ominous words "non-numerical value" ;-)
In fact, you asked Mathematica kinda to find the numeric value of
the expression x without defining x. You cannot do it, Mathematica
cannot do it, nobody can do it.
Best wishes,
Vladimir
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Vladimir Bondarenko
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