Hello,
Well, variable period functions are listed in one page because in the past it
was requested to have them listed in one place.
But... I see your point and I agree that some ("most" is debatable) people may
want to have it the other way.
Best regards,
Tomasz Janeczko
amibroker.com
On 2010-07-15 16:25, rise_t575 wrote:
>
> Hello,
>
> A short definition within each page of the AFL Function Reference/AB manual
> what type of parameter (scalar/array) is expected/allowed for the
> corresponding function would be a better place for this old known fact.
> That's where most people look at in such cases.
>
> --- In [email protected], Tomasz Janeczko<gro...@...> wrote:
>> Hello,
>>
>> It is old, known fact. Some functions accept variable periods. Documented in
>> the manual:
>>
>> http://www.amibroker.com/guide/a_varperiods.html
>>
>>
>> Best regards,
>> Tomasz Janeczko
>> amibroker.com
>>
>> On 2010-07-15 08:12, Mike wrote:
>>> Interesting. I ran a quick test and it seems to suggest that Sum does in
>>> fact take an array as second argument, contrary to expectations.
>>>
>>> It would appear that you are correct, with respect to Sum. Though it is not
>>> always the case that a function with a "periods" argument will accept an
>>> array. For those that don't, you will have to find another approach.
>>>
>>> Here's my test:
>>>
>>> Test = Sum(1, Cum(1));
>>> Fixed = Sum(1, 5);
>>>
>>> Plot(Test, "Test", colorRed, styleLine);
>>> Plot(Fixed, "Fixed", colorBlue, styleLine);
>>> Title = "Bar: " + BarIndex() + ", Test: " + Test + ", Fixed: " + Fixed;
>>>
>>> If Sum did not accept an array, but was instead substituting some fixed
>>> number (e.g. last element of the array), then both Plots should result in
>>> flat lines. However, the test clearly shows that the Test plot rises at a
>>> 45 degree angle indicating that the period is different at each bar.
>>> Compare that to the Fixed plot which is constant at a level of 5.
>>>
>>> Mike
>>>
>>> --- In [email protected], "aaryan111"<aaryan111@> wrote:
>>>> I guess, sum() is behaving the ideal way :),
>>>>
>>>> The most important thing here is,
>>>> AMIBROKER being an array processing language, calculates all the elements
>>>> of array , but at any given active bar, it fetches the current value from
>>>> the whole arry index and shows it to us,Presumably using some barindex
>>>> kind of mechanism internally.
>>>>
>>>> When we put close, open or any array in any afl , like ((close + open +
>>>> High + Low )/4= MAVG),amibroker produces output based on the current
>>>> value of that array, we dont need to specify current index of that array
>>>> (scalar value) to get output at any current bar,it manages it intenally.
>>>>
>>>> Here its impotant to not that, its IRRELEVANT if we use array in a
>>>> Function or simply put it in any statement in afl, it fetches a scalar
>>>> value out of that produced array to show it to us.
>>>>
>>>> when I put SUm(close,Barssince()) It ideally fetches the current element
>>>> of BarsSince array and place it over ther.
>>>>
>>>> This is the ideal way. Sum() is behaving the IDEAL way.
>>>> infact every other function,
>>>> let it be ,
>>>> MA(Close,BarsSince(TimeNum()< 093000));
>>>> or any other function, having Periods, as a second argument.
>>>>
>>>> While in Stdev(),it simply goes against the normal behaviour.
>>>> it should infact, in MUST , point to the current active element of the
>>>> Barssince(), let it be a 0 or any other value, its irrelevant, its still a
>>>> scalar.
>>>> and it simply doesnt do that!.
>>>>
>>>> i think i have made my point clear now.
>>>>
>>>> Wave : Lastvalue() will surely fetch the last element of the array, but i
>>>> cant use it while testing it offline, i will get all future values of that
>>>> array, its all fine if i have to use it while online updation.
>>>>
>>>>
>>>>
>>>> Regards...
>>>>
>>>>
>>>> --- In [email protected], "wavemechanic"<olesmithy@> wrote:
>>>>> I'm fairly sure that the only way you will get StDev() to accept
>>>>> BarsSince() in the 2nd argument without complaining is to force the
>>>>> return of a number by use of LastValue() or SelectedValue(). I don't
>>>>> know why Sum() is not complaining when BarsSince() is used.
>>>>>
>>>>> In the Sum() case, I think that BarsSince( TimeNum ... ) is returning a
>>>>> constant array based on the bar you select, including the last bar if no
>>>>> bar is selected. If so, that would work OK but does not explain why
>>>>> StDev() does not work.
>>>>>
>>>>> For Sum(), if you replace TimeNum() with another array generator, for
>>>>> example, MA( C, 13 ) == ...., Sum() still does not complain but
>>>>> BarsSince() returns 0 (I believe) and, hence, Sum() is 0.
>>>>>
>>>>> You might have stumbled onto a unique situation but I would not assume
>>>>> that it can be generalized and would always go for ensuring the return of
>>>>> a number from the 2nd argument whether or not the above is correct.
>>>>>
>>>>> Bill
>>>>> ----- Original Message -----
>>>>> From: aaryan111
>>>>> To: [email protected]
>>>>> Sent: July 14, 2010 3:08 PM
>>>>> Subject: [amibroker] Re: Sum and Stdev , wierd behaviour of stdev
>>>>>
>>>>>
>>>>> Hi , thanx for the feedback wave.
>>>>> its Syntax is basically to put Period as 2nd argument.
>>>>> When u put an array in SUM() as 2nd argument, it will take the
>>>>> corresponding scalar frm that array and apply it as a filter.
>>>>>
>>>>> i have successfully executed this
>>>>>
>>>>> Sum(Close,BarsSince(TimeNum()>092400));
>>>>>
>>>>> regards
>>>>>
>>>>>
>>>>> --- In [email protected], "wavemechanic"<olesmithy@> wrote:
>>>>> >
>>>>> > Neither takes array as 2nd. See syntax in Users Guide.
>>>>> > ----- Original Message -----
>>>>> > From: aaryan111
>>>>> > To: [email protected]
>>>>> > Sent: July 12, 2010 3:41 PM
>>>>> > Subject: [amibroker] Sum and Stdev , wierd behaviour of stdev
>>>>> >
>>>>> >
>>>>> > Hi Everybody,
>>>>> >
>>>>> > Both Sum() and Stdev() Functions Have same Arguments
>>>>> Structure.but when i put
>>>>> > Sum(Close,BarsSince(TimeNum()>092400))
>>>>> > it executes successfully,while
>>>>> > Stdev(Close,BarsSince(TimeNum()>092400))
>>>>> > gives a warning " Function Expects Different type of argument
>>>>> here " .
>>>>> >
>>>>> > as far as i understand , both can take array as 2nd argument
>>>>> and amibroker will automatically fetch the current running index value of
>>>>> that array as the 2nd argument, same as it does with other functions.
>>>>> >
>>>>> > one can put any other function returning array like barindex()
>>>>> in 2nd argument , result will be same.
>>>>> >
>>>>> > Any suggestions??
>>>>> >
>>>>> > Regards,
>>>>> >
>>>>> >
>>>>> >
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>>> This group is for the discussion between users only.
>>> This is *NOT* technical support channel.
>>>
>>> TO GET TECHNICAL SUPPORT send an e-mail directly to
>>> SUPPORT {at} amibroker.com
>>>
>>> TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
>>> http://www.amibroker.com/feedback/
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>>>
>>> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
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>
>
>
> ------------------------------------
>
> **** IMPORTANT PLEASE READ ****
> This group is for the discussion between users only.
> This is *NOT* technical support channel.
>
> TO GET TECHNICAL SUPPORT send an e-mail directly to
> SUPPORT {at} amibroker.com
>
> TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
> http://www.amibroker.com/feedback/
> (submissions sent via other channels won't be considered)
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> Yahoo! Groups Links
>
>
>
>
