Bob,
Thanks! Your hint was exactly what I needed, to help me make my output
"imaginary-zero-restorer" function.
zr =. (' ';'j')rplc~ ] NB. use the "string replace" verb to put the
'j' back in the complex number.
zr '1 0'
1j0 NB. we can do it!
Just need to get the real & imaginary parts of a complex number into a text
string. Robert showed us how to do that:
+. 1j0
1 0
$ +. 1j0
2
NB. Got the complex parts as two separate numbers,
thanks to Robert. Now convert to a string.
": +. 1j0
1 0 NB. This is a string.
$ ": +. 1j0
3 NB. See? A string 3 characters long.
zr ": +. 1j0
1j0 NB. Eureka! We did it. The Zero Restorer verb!
$ zr ": +. 1j0
3 NB. Of course, the zero-restored display is a
string as well. It has to be, for J to display the zero.
zr ": +. _3.1j0.5
_3.1j0.5 NB. Our Zero Restorer doesn't affect the display of
other complex numbers.
". zr ": +. 1j0
1 NB. Of course if you let J display the complex
number natively, it steals the zero.
Is there a more compact way to define the Zero Restorer verb? The
string-replace function is probably overkill for what we want to do, and I
haven't figured out how to include the Real/Imaginary (+. ) and the Format
(":) inside the Zero Restorer Function.
When you think about it, something like J's complex notation is the kind of
notation that you would need for a native unum-based computational system.
We don't want to use 'j' for the separator, it's already taken. What if we
defined a new number format in J, the unum format, that used a 'u' instead
of a 'j' for intervals. 4 bit unums would look something like this:
UNUMS
┌──┬─────┬──┬─────┬──┬───────┬────┬──────┬─┬─────┬───┬─────┬─┬───┬─┬───┐
│__ │ __u_2 │ _2│_2u_1 │_1 │ _1u_1r2 │ _1r2 │ _1r2u0 │0│ 0u1r2 │
1r2 │ 1r2u1 │ 1 │1u2 │2│ 2u_ │
└──┴─────┴──┴─────┴──┴───────┴────┴──────┴─┴─────┴───┴─────┴─┴───┴─┴───┘
If this was a native format, then we could just do all our unum
calculations easily. No notation hassle.
Skip
Skip Cave
Cave Consulting LLC
On Thu, Aug 18, 2016 at 11:58 PM, robert therriault <[email protected]>
wrote:
> Hey Skip,
>
> You could capture that structure yourself using +. couldn't you? It may
> not be as nice as having the display done
> natively, but the information is not really thrown away.
>
> +. 3j0
> 3 0
> +. 3
> 3 0
>
> Cheers, bob
>
> > On Aug 18, 2016, at 9:44 PM, Skip Cave <[email protected]> wrote:
> >
> > If we did have a display verb that could always show the
> > zero-imaginary-part of complex numbers in storage, then we would have to
> > use that verb every time we displayed output that might be complex, if we
> > wanted to see any zero imaginary part.
>
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