More 1st impressions while learning J--please feel free to give me
the truth values for any of my statements
I just tried the second link John forwarded and like Henry, I was
confronted by a lot of question marks in black diamonds (from the
Glyph catalogue) as Henry mentioned. Has someone alerted whoever
supports this web-page (View source :http://www.jsoftware.com/books/
help/jforc/applied_mathematics_in_j.htm#_Toc129570854 ).
Copying and pasting restores the intended text:
Radix Notation For Numbers
Numbers in radix form comprise a multiplier, a base, and an
exponent, written together with no spaces; the value of the number
is multiplier * base ^ exponent . The base is indicated by a
letter, chosen from e (base 10), p (base π, 3.14159...), or x (base
e, 2.71828...). Examples:
1p1
3.14159
1x1
2.71828
1e3
1000
While p (π) and x (e) and j (are constants which it makes sense as
globals and to use in radix notation
There seems to be something wrong with my math or with implementation
of imaginary numbers or these expressions should all yield 1j1 or
_1j1 (or domain error)
_1^1r2
_1.27104e_15j1
_1^0.5
0j1
1j1
1j1
e is a trivial constant as it is the default base 10. It's raison
d'être seems to be that in J the default display for Scientific
notation uses e. Used with radix notation, the useful range is
limited and may create more rather then less problems where sensitive
to comparison tolerance. For example:
1e6*1%3
333333
1e7*1%3
3.33333e6
r seems to be a backhand way for declaring type to be Rational and
its useful range is also limited--see Thread "am I going crazy" ( it
seems to me that type is not normally declared in J but defaults in
an efficient way)
b is a trivial constant if it represents 2 and breaks the mold of
multiplier, base, exponent being instead more of a function than a
constant based on the APL primitive that I guess was named base (am I
still way off base?)
Donna
[EMAIL PROTECTED]
On 14-Jun-06, at 9:55 AM, Henry Rich wrote:
The exponential numeric constants are explained in the system
documentation
http://www.jsoftware.com/books/help/dictionary/dcons.htm
and in Henry Rich's book
http://www.jsoftware.com/books/help/jforc/applied_mathematics_
in_j.htm#_Toc129570854
The text of my book pointed to by the link above seems to have
a bunch of ? characters when I look at it. To see a clean copy,
bring up a J system, then Help|Help, click 'J for C Programmers',
then go to the Applied Mathematics chapter.
Henry Rich
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