• To: mathgroup at smc.vnet.net
• From: Alois Steindl <Alois.Steindl at tuwien.ac.at>
• Date: Sat, 25 Jul 2009 04:18:03 -0400 (EDT)

```angela schrieb:
> mechanism = NDSolve[{
>     s'[t] == -k1f  s[t] b2[t] + k1r c[t],
>     c'[t] == k1f [a] [s] - k1r c[t],
>     p'[t] == k2[c] == bp[t] == b'[t],
>     a'[t] == -k1f a[t] s[t] + k1r c[t],
>     b2'[t] == -k1f s[t] b2[t] + k2f c[t],
>     s[0] == 0.005;
>     b[0] == 0.025;
>     p[0] == 0;
>     bp[0] == 0;
>     b[0] == 0}
>    /. {k1f -> 0.1, k1r -> 0.01, k2 -> 1},
>   {b2, s, c, p, b, bp},
>   {t, 0, 1500}]
>
>
> NDSolve::deqn: Equation or list of equations expected instead of True \
> in the first argument {s^\[Prime][t]==0.01 c[t]-0.1 b2[t] \
> s[t],<<4>>,True}. >>
>
Hello,
the line starting with p'[t] doesn't look proper.

Just an additional remark: Is k2 a function of c? If that is the case,
you would have to replace k2[c] by k2[c[t]].

If I encounter problems with NDSolve, I first look at the differential
equation itself (I just input the first entry of NDSolve.) Many errors
can be detected that way, at least here.
Alois

```

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