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RE: differential equation solve

• To: mathgroup at smc.vnet.net
• Subject: [mg68834] RE: [mg68821] differential equation solve
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 21 Aug 2006 03:27:27 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

You didn't give a sample input statement for the case where you got the
first error message. Post that and you will obtain a better answer.

As for the latter two equations, they both returned solutions on my systems,
one with a warning message. You didn't show the output that you got.

Maybe you could state the problem more clearly with both input and output?

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: elvis [mailto:rapstone at gmail.com]
To: mathgroup at smc.vnet.net


Here we often use mathematica to solve differential equations, when I
encouter a equation with several constrains I set them to those values.
But it cannot solve it and have the following warnings:

    DSolve::deqx: Supplied equations are not differential equations of
the given functions.

Give a very simple differential equation here:

  DSolve[{y'[x] == r*y[x], y[0] == a}, y, x]

another equation:

\!\(DSolve[{\(x'\)[t] == r*x[t] \((1 - x[t]\/xm)\), x[0] == x0}, x,
t]\)

this face anothe prolbem

Can anyone help to "solve" this problem for me?
Thanks!