# Question:Another strange behavior for numeric solution of ODE

## Question:Another strange behavior for numeric solution of ODE

Maple

Hi all,

```> deq := diff(x(t), t) = 3*x(t)/t+(9/2)*t-13;

d         3 x(t)   9
deq := --- x(t) = ------ + - t - 13
dt          t      2
> ci := x(3) = 6;

ci := x(3) = 6
> p := dsolve({ci, deq}, x(t), numeric);

p := proc(x_rkf45)  ...  end;
> plots[odeplot](p, view = [-1 .. 4, -10 .. 10]);

```

```> p(0);

[                                     -8]
[t = 0., x(t) = 8.65023735199754930 10  ]```

but if I do:

```> q := dsolve({ci, deq}, x(t), type = numeric, method = taylorseries);

q := proc(x_taylorseries)  ...  end;
> plots[odeplot](q, view = [-1 .. 4, -10 .. 10]);

> q(0);

[t = 0., x(t) = 0.]
> solex := rhs(dsolve({ci, deq}, x(t)));

9  2   13      3
solex := - - t  + -- t + t
2      2

```

But in cases where I don't know the answer, which should I trust?  here is another one

```> deq := diff(x(t), t) = 1-t-x(t)/t;

d                 x(t)
deq := --- x(t) = 1 - t - ----
dt                 t
> ci := x(1) = 0;

ci := x(1) = 0
> q := dsolve({ci, deq}, x(t), numeric);

q := proc(x_rkf45)  ...  end;
> q(0);

[t = 0., x(t) = 1.73003351210698475]
> plots[odeplot](q);

> solex := rhs(dsolve({ci, deq}, x(t)));

1  2   1      1
solex := - - t  + - t - ---
3      2     6 t
> plot(solex, t = -1 .. 1, -100 .. 100);

and for the finish

> r := dsolve({ci, deq}, x(t), numeric, method = taylorseries);

r := proc(x_taylorseries)  ...  end;
> plots[odeplot](r);
%;
Warning, could not obtain numerical solution at all points, plot may be incomplete

```
```> r(0);
```
```Error, (in r) cannot continue integration past t=0.585794295977905e-4, step size dropped below minimum

```
` `

Thanks in advance for any help

Mario

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