[SciPy-User] Computing derivatives with scipy.integrate.odeint

[Camille Chambon]

Thanks very much! It's now clear for me.
Camille

Le 28/05/2015 14:24, Gyro Funch a écrit :
> On 2015-05-28 2:34 AM, Camille Chambon wrote:
>> Hello,
>>
>> I'm trying to understand how scipy.integrate.odeint works.
>>
>> I wrote the following example:
>>
>> import numpy as np
>> from scipy.integrate import odeint
>> y0 = [2]
>> def func(y, t):
>>      return [y[0]]
>> t = np.arange(0, 4.0, 1.0)
>> y = odeint(func, y0, t)
>> print 'y', y
>>
>> It prints:
>> y [[  2.        ]
>>   [  5.43656382]
>>   [ 14.77811278]
>>   [ 40.17107594]]
>>
>> Why don't I get:
>> y [[  2.        ]
>>   [  4.]
>>   [ 8.]
>>   [ 16.]]
>>
>> ?
>>
>> My question is probably due to my limited knowledge in basic
>> mathematics.
>>
>> Thanks for your help.
>>
>> Camille
>>
>
> Hello Camille,
>
> The way that 'func' is written, you are solving the differential
> equation
>
> dy/dt = y ; y(0) = 2 ,
>
> which has the solution y = 2 * e^t.
>
> -gyro
>
>
>
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