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Tomasz,
The proposed functions sound good and would be far more convenient than
IIFs.
But....(why is there always a but?).. if I forget to use the appropriate
function in my code (i.e. I do not *anticipate* the condition) then will the
AFL engine display a Divide by Zero error message when I attempt to plot or
use the code? If it does not then my concern is the condition will go
undetected. IMO AFL engine should display message identifying the errror and
bar - the user can then take appropriate action - either adding one of the
proposed new functions to code or correcting the basic logic error in code.
Sorry to go on about this but I just don't like the idea of "errors" going
unreported.
John
----- Original Message -----
From: "Tomasz Janeczko" <amibroker@xxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Tuesday, March 04, 2003 8:42 AM
Subject: Re: [amibroker] Re: [Tomasz] 1 / 0 = 0? : NaN or Infinity would be
good
> John,
>
> In the case you mentioned a very high value (+infinite) will be plotted.
>
>
> I was thinking about adding function like
>
> IsNan( array/number ) - detects NaN or
> IsFinite( array/number ) - detects if the number is finite (not Nan nor
infinite)
>
> Best regards,
> Tomasz Janeczko
> amibroker.com
> ----- Original Message -----
> From: "John" <jr-sw@xxxxxxxxxxxxxxxxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Tuesday, March 04, 2003 1:27 AM
> Subject: Re: [amibroker] Re: [Tomasz] 1 / 0 = 0? : NaN or Infinity would
be good
>
>
> > Tomasz or anyone else,
> >
> > Sorry but I am still clear how the proposed handling of Divide by Zero
> > errors is going to work.
> >
> > What happens if for example we write some AFL custom indicator code
like:-
> >
> > x=(H-L)/(C-L);
> >
> > When the Close is very near but not equal to the Low indicator plot
value
> > will be big. But when the Close matches the Low exactly the indicator
plot
> > value drops to Zero? I know this is the current AFL behaviour becuase I
have
> > been caught out by it before ;-)
> >
> > For the indicator to follow a logical progression IMO it should plot a
> > bigger value when C-L is zero. So how will this be handled? Obviously
one
> > can write code to defend against anticipated zero divides (my Metastock
> > indicators are full of these <g>) but without some error message from
the
> > AFL engine it seems to me un-anticipated zero divides will get by
> > un-noticed.
> >
> > I am probably missing something here - it's late!
> >
> > John
> >
> > ----- Original Message -----
> > From: "Tomasz Janeczko" <amibroker@xxxxxx>
> > To: <amibroker@xxxxxxxxxxxxxxx>
> > Sent: Monday, March 03, 2003 6:41 PM
> > Subject: Re: [amibroker] Re: [Tomasz] 1 / 0 = 0? : NaN or Infinity would
be
> > good
> >
> >
> > > John,
> > >
> > > I don't think so.
> > >
> > > 1/0 will still be displayed as {NaN}
> > >
> > > But statement like this
> > >
> > > 100 / ( 1/ 0 )
> > >
> > > will give zero, which is correct considering the fact
> > > that it could be rewritten to:
> > >
> > > 0 * 100/1
> > >
> > > Best regards,
> > > Tomasz Janeczko
> > > amibroker.com
> > > ----- Original Message -----
> > > From: "John" <jr-sw@xxxxxxxxxxxxxxxxx>
> > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > Sent: Monday, March 03, 2003 7:17 PM
> > > Subject: Re: [amibroker] Re: [Tomasz] 1 / 0 = 0? : NaN or Infinity
would
> > be good
> > >
> > >
> > > > Tomasz,
> > > >
> > > > If you take an automatic approach in AFL engine to Divide by Zero
errors
> > > > then won't any genuine user logic/coding errors get masked?
> > > >
> > > > John
> > > > ----- Original Message -----
> > > > From: "Tomasz Janeczko" <amibroker@xxxxxx>
> > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > Sent: Monday, March 03, 2003 5:26 PM
> > > > Subject: Re: [amibroker] Re: [Tomasz] 1 / 0 = 0? : NaN or Infinity
would
> > be
> > > > good
> > > >
> > > >
> > > > > Mike,
> > > > >
> > > > > A next beta (4.29.8) will give you 100.
> > > > >
> > > > > Best regards,
> > > > > Tomasz Janeczko
> > > > > amibroker.com
> > > > > ----- Original Message -----
> > > > > From: <mik-u@xxxxxxxxxxx>
> > > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > > Sent: Monday, March 03, 2003 6:20 PM
> > > > > Subject: [amibroker] Re: [Tomasz] 1 / 0 = 0? : NaN or Infinity
would
> > be
> > > > good
> > > > >
> > > > >
> > > > > > Hi Tomasz,
> > > > > >
> > > > > > NaN or Infinity would be good. I just need something to check an
> > > > > > exception and get correct value (100) when calculating formula
like
> > > > > > this:
> > > > > >
> > > > > > 100 - 100 / (1 + 30 / 0)
> > > > > >
> > > > > > Regards,
> > > > > > Mike
> > > > > >
> > > > > > --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko"
<amibroker@xxxx>
> > > > > > wrote:
> > > > > > > Hello,
> > > > > > >
> > > > > > > When I am thinking more on this... maybe it would be better
> > > > > > > to display a special string "NaN" in such case?
> > > > > > >
> > > > > > > I will modify the WriteVal and this division handling so
> > > > > > > it displays NaN string so it is more obvious what happens.
> > > > > > >
> > > > > > > Best regards,
> > > > > > > Tomasz Janeczko
> > > > > > > amibroker.com
> > > > > > > ----- Original Message -----
> > > > > > > From: "Tomasz Janeczko" <amibroker@xxxx>
> > > > > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > > > > Sent: Monday, March 03, 2003 8:57 AM
> > > > > > > Subject: Re: [amibroker] [Tomasz] 1 / 0 = 0?
> > > > > > >
> > > > > > >
> > > > > > > > Hello,
> > > > > > > >
> > > > > > > > (30/0) is NaN - NOT a NUMBER
> > > > > > > >
> > > > > > > > Division by zero is illegal operation.
> > > > > > > >
> > > > > > > > If there was no protection against dividing by zero
> > > > > > > > the program would just bomb out (crash and say good bye).
> > > > > > > >
> > > > > > > > Therefore when dividing two numbers X / Y AB checks
> > > > > > > > if Y is equal to zero and always returns zero in that case.
> > > > > > > >
> > > > > > > >
> > > > > > > > Best regards,
> > > > > > > > Tomasz Janeczko
> > > > > > > > amibroker.com
> > > > > > > > ----- Original Message -----
> > > > > > > > From: <mik-u@xxxx>
> > > > > > > > To: <amibroker@xxxxxxxxxxxxxxx>
> > > > > > > > Sent: Monday, March 03, 2003 4:00 AM
> > > > > > > > Subject: [amibroker] [Tomasz] 1 / 0 = 0?
> > > > > > > >
> > > > > > > >
> > > > > > > > > Tomasz,
> > > > > > > > >
> > > > > > > > > AB returning 0 for an expression like 1 / 0. Is it
correct?
> > > > > > > > >
> > > > > > > > > The following expression
> > > > > > > > >
> > > > > > > > > 100 - 100 / (1 + 30 / 0)
> > > > > > > > >
> > > > > > > > > is equal 0 in AB, but I think it should be equal 100.
> > > > > > > > >
> > > > > > > > > Thanks,
> > > > > > > > > Mike
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
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