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 on this topic.
Sample google search:
site:jsoftware.com inurl:nuvoc complex
Quite a bit of reading there, if you have the patience for it (be sure
to mix in plenty of trial and error, though, or it's a total snoozer).
Thanks,
--
Raul
On Fri, Jun 30, 2017 at 11:30 PM, Rob Hodgkinson <[email protected]> wrote:
> Hi Lawrence, the âill-formed numberâ is
because "j." is a verb, quite different to
âjâ which is part of a noun construct (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 âj.â verb
with a space either side to make it clear to J
that this is not â1jxxxâ where J would
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 âcomplex constantsâ entered
directly using the j notation (as a continuous sequence of non-blank chars)â¦
> 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 on this 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 am
using j64-804 on ubuntu 12.04. I am either
doing something really stupid or I need to
update to 806. Updating anything gives me
heartburn or worse 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 the Dictionary 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 see http://www.jsoftware.com/forums.htm
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
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