Re: [Jprogramming] Complex Number Problems

Don Kelly Sat, 01 Jul 2017 20:42:07 -0700

It appears that the construct 2r.2 is not described in NuVoc and thatit is , in fact equivalent to 2%0.2 or 20r2. it is similar to 1p.2==1p0.2 or pi to the power of 0.2

you are dealing with nouns in either case and there is a built inconversion that allows the use of 2r.2 to be treated as 2 % 0.2 and theresult is a floating point number (example 2r.3 is 6.66667 - the same as2r0.3) not a rational number

In the case of j we have 2j0.2 the same as 2j.2 interpreted as above.in both cases the term is a noun expressing a complex number equivalentto 2+ j.0.2.

x r. y and x j. y behave the same as the r. and j. are verbs acting onx and y are nounsbut xr.y and xj.y are nouns. There is an inconsistency in this withrespect normal appli cation of 0.n rather than .n


0.2 j. 0.2

0.2j0.2


.2j.2


.2j0.20000000000000001

At least that is my take on this.

Don Kelly



On 2017-07-01 4:34 AM, Martin Kreuzer wrote:

Looking at (r.) Angle, which is a verb somewhat similar to (j.)Complex, I get
   2 r. 0.2
1.96013j0.397339
   2 r.0.2
1.96013j0.397339
   2 r. 2
_0.832294j1.81859
   2 r.2
_0.832294j1.81859
which all four look fine to me, but are not constistent with (j.)'sbehaviour, that's been my point ...
and then there is this construct

   2r.2
10
which doesn't have anything to do with (r.) Angle but is a(fractional) constant of value 2/0.2 showing another instance of .2being interpreted as 0.2 which is not accepted in other circumstances.
-M

At 2017-07-01 10:50, you wrote:
this is parsed as a token
   ;:'3e.4'
+----+
|3e.4|
+----+
but it (rightfully?) throws an error
   3e.4
|ill-formed number

this is also parsed as a token
   ;:'3j.4'
+----+
|3j.4|
+----+

the behavior seems endemic
   3p.4
4.74221
   3ad.4
2.99993j0.0209438
   3ar.4
2.76318j1.16826
   3x.4
4.47547
   3b.4
1.33333

I think either 3e.4 should be legal or all others should be illegal
for consistent.

Ð¡Ð±, 01 Ð¸ÑÐ» 2017, Martin Kreuzer Ð½Ð°Ð¿Ð¸ÑÐ°Ð»(Ð°):
> Looking at the examples, I came across the difference between
>
>    3 j. 4      NB. spaces
> 3j4
>
> and
>
>    3j.4      NB. no spaces
> 3j0.4
>
> Given that this (rightfully) throws an error
>
>    .2 .3 .4 .5
> |syntax error
> |        .2 .3 .4 .5
>
>  while this doesn't
>
>    0.2 0.3 0.4 0.5
> 0.2 0.3 0.4 0.5
>
> why then is the construct  3j.4 valid..?
>
> -M
>
>
> At 2017-07-01 04:43, you wrote:
>
> > > As Henry points out, the NuVoc page is quite a bit clearer onthis topic.
> >
> > Sample google search:
> >    site:jsoftware.com inurl:nuvoc complex
> >
> > Quite a bit of reading there, if you have the patience for it (besure> > to mix in plenty of trial and error, though, or it's a totalsnoozer).
> >
> > Thanks,
> >
> > --
> > Raul
> >
> >
> > On Fri, Jun 30, 2017 at 11:30 PM, Rob Hodgkinson<[email protected]> wrote:> > > Hi Lawrence, the Ã¢ÂÂill-formed numberÃ¢ÂÂ is because "j."is a verb,> > quite different to Ã¢ÂÂjÃ¢ÂÂ which is part of a nounconstruct (like 3j4,
> > or 1e3 for 1000).
> >
> > > So in your examples ...
> >
> > > NB. But wait, not so fast:
> > >   1j.(2^0.5)%2
> > > |ill-formed number
> > > NB. No
> >
> > > NB. Now try to separate the Ã¢ÂÂj.Ã¢ÂÂ verb with a spaceeither side to> > make it clear to J that this is not Ã¢ÂÂ1jxxxÃ¢ÂÂ where Jwould assume you
> > are trying to make a complex constant.
> > >    1 j. (2^0.5)%2
> > > 1j0.707107
> >
> > > The reason is that J can also directly interpret Ã¢ÂÂcomplex
> > constantsÃ¢ÂÂ entered directly using the j notation (as acontinuous
> > sequence of non-blank chars)Ã¢ÂÂ¦
> > >    3j4    NB. This is a single complex constant 3+i4
> > > 3j4
> >
> > > 3 j4 NB. But now J tries to view this as a list of (3)and (j4)
> > which which J would assume is (3) and a variable called (j4).
> > > |syntax error
> > > | 3 j4
> >
> > > As Henry points out, the NuVoc page is quite a bit clearer onthis topic.
> >
> > > HTH, Regards Rob
> >
> >
> > >> On 1 Jul 2017, at 1:14 pm, Lawrence Wickert<[email protected]>
> > wrote:
> > >>
> > >> Hello,  I am a old EE still trying to learn. I am a real beginner
> > having no end of problems with specifying complex numbers. I amusing> > j64-804 on ubuntu 12.04. I am either doing something reallystupid or I> > need to update to 806. Updating anything gives me heartburn orworse so> > I hope it is just my misunderstanding of basic principles.Although I> > have a bad habit of RTFM as a last resort I have tried theDictionary to
> > no avail.  I appreciate any guidance.
> > >>
> > >>   0j(2^0.5)%2
> > >> |ill-formed number
> > >>
> > >>   0j((2^0.5)%2)
> > >> |ill-formed number
> > >>
> > >>   j.(2^0.5)%2
> > >> 0j0.707107
> > >> NB. Eureaka, OK, I get it!
> > >>
> > >> NB. But wait, not so fast:
> > >>   1j.(2^0.5)%2
> > >> |ill-formed number
> > >> NB. No
> > >>
> > >>   1j(2^0.5)%2
> > >> |ill-formed number
> > >> NB. Still No
> > >>
> > >>   1+j.(2^0.5)%2
> > >> 1j0.707107
> > >> NB. This works!
> > >>
> > >> Let's try to do something with it:
> > >>   k=:(0 1+j.(2^0.5)%2 3 4 0 5)
> > >> |length error
> > >> |   k=:(0 1    +j.(2^0.5)%2 3 4 0 5)
> > >>
> > >> NB. Maybe parantheses will help:
> > >>   k=:(0 (1+j.(2^0.5)%2) 3 4 0 5)
> > >> |syntax error
> > >> |   k=:(    0(1+j.(2^0.5)%2)3 4 0 5)
> > >>
> > >> NB. This one has to work:
> > >>   k=:(0 1j0.7071 3 4 0 5)
> > >>   k
> > >> 0 1j0.7071 3 4 0 5
> > >> NB. It does but it can't be the only way to do it.
> > >>
> > >> NB. One last rry:
> > >>   g=: 1+j.(2^0.5)%2
> > >>   g
> > >> 1j0.707107
> > >> NB. That's nice.
> > >>
> > >>   k=:(0 g 3 4 0 5)
> > >> |syntax error
> > >> |   k=:(    0 g 3 4 0 5)
> > >> NB. This isn't nice.
> > >>
> > >> Lost in the high desert of New Mexico, Larry Wickert
> > >>
> > >>----------------------------------------------------------------------> > >> For information about J forums seehttp://www.jsoftware.com/forums.htm
> >
> > >----------------------------------------------------------------------> > > For information about J forums seehttp://www.jsoftware.com/forums.htm> >----------------------------------------------------------------------> > For information about J forums seehttp://www.jsoftware.com/forums.htm
>
> ----------------------------------------------------------------------
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--
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Re: [Jprogramming] Complex Number Problems

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