On Tue, Mar 30, 2010 at 7:01 PM, G B <[email protected]> wrote:
> Apologies for being dense, but I'm missing something.  All three forms
> ( f(x), def f(x) and f=lambda x: ) are giving the same results.
>
>
> Trying:
> ---------
> var('x')
> T=RealDistribution('gaussian',1)
> def f(x):
>    return sin(x)+ T.get_random_element()
> plot(f(x),(x,0,2*pi))
> ---------
>
> and
> --------
> var('x')
> T=RealDistribution('gaussian',1)
> f=lambda x: sin(x)+ T.get_random_element()
> plot(f(x),(x,0,2*pi))
> ---------
>
> all give me a clean sine with a random offset, rather than sine
> +noise...

Use

  plot(f, (0,2*pi))

William

>
>
>
> On Mar 30, 2:30 pm, William Stein <[email protected]> wrote:
>> On Tue, Mar 30, 2010 at 2:21 PM, G B <[email protected]> wrote:
>> > Hi--
>>
>> > I'm trying to figure out how to use RealDistributions to model noise.
>> > For example, I would like to model a signal+noise and tried using this
>> > construct:
>>
>> > T=RealDistribution('gaussian',1)
>> > f(x)=sin(x)+T.get_random_element()
>> > plot(f(x),(x,0,2*pi))
>>
>> > Unfortunately, that only calls get_random_element() once, at the
>> > definition of f(x) and results in a perfect sinusoid offset by a
>> > random value.
>>
>> def f(x):
>>      return sin(x) + T.get_random_element()
>>
>> or
>>
>>  f = lambda x : sin(x) + T.get_random_element()
>>
>> William
>>
>>
>>
>> > How do I write this so that get_random_element() is called each time
>> > f(x) is evaluated?  I would like to see a noisy sinusoid.
>>
>> > Thanks--
>> >  Greg
>>
>> > --
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>>
>> --
>> William Stein
>> Associate Professor of Mathematics
>> University of Washingtonhttp://wstein.org
>
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-- 
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org

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