This page is for testing. The contents can be expunged at any time.

'Test'

-- BillLam 2010-02-10 15:22:34

E
0 1 5 2 3 4 6

E
0 1 5 2 3 4 6

E
0 1 5 2 3 4 6

 column 0 column 1 column 2 0 zero zilch 1 one eins 2 two zwei

Notation as a Tool of Thought, Figure 3.

Let be the set of primes such that , and let . Then the number of semiprimes less than or equal to is given by

Something is still amiss in the formula. For

to be true, it must be that

But:

   pi=: _1&p: + 1&p:
] p=: p: i.m=: 5
2 3 5 7 11
pi p
1 2 3 4 5
+/ pi p
15
2 %~ m*m-1
10

The following is generated by <<RandomQuote(Doc/A Programming Language)>>

 No quotes on Doc/A Programming Language.

-- RogerHui 2007-10-28 03:35:43

a b c d

 k-origin indexing; k+i.n in J outer product; the dyad +/ in J the number of rows in matrix ; #M in J the number of columns in matrix ; {:$M in J equivalent to ,B#"1 M in J equivalent to ,B#"1&|:M in J The formula computes the diagonal of a rectangle with sides and Tip: The system replaces @SIG@ in the text by your UserName and current timestamp. ## User Suggestions This is very cool Roger. Embedded latex. This Wiki stuff is deeper than I thought. JohnBaker Actually this whole page is for just testing. Do you recognize the expressions? RogerHui No. JohnBaker The story behind is recounted on page 25 of A Source Book of APL. In the Q&A session after Ken Iverson's presentation of Formalism in Programming Languages at the Working Conference on Mechanical Language Structures in 1963, Dijkstra asked, "How would you represent a more complex operation, for example, the sum of all elements of a matrix which are equal to the sum of the corresponding row and column indices?" The above formula was Ken's one-liner answer. It was in Iverson notation (APL did not yet exist). According to the notation in A Programming Language, a valid answer would be (Two slashes instead of one in front of the final would also work.) I think a conversant APL or J user would agree that Dijkstra's question was very simple, so I don't think Ken would have had any trouble, and attribute the first version to clerical errors. Signed with "at SIG at" as a test. -- RogerHui 2005-10-14 13:35:30 I'd define dijkstra =:$ (] +/@:= (+/@#: i.@:#)) , in J.

Very very cool - practically cryogenic. Suggest changing Tex & LaTex to the officially approved TeX & LaTeX, including modifying the name of the nascent JWiki LaTex page. EwartShaw

Done. -- RogerHui 2005-10-14 15:51:35

Still can't get the hang of when LaTeX goes to a new line and when it doesn't. -- RogerHui 2005-10-14 16:28:52

See new page for a how to -- ChrisBurke 2005-10-16 08:49:32