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From: vpcsc4@sfsuvax1.sfsu.edu (Emmett McLean)
Subject: J Questions
Message-ID: <1992Jun11.211513.29040@csus.edu>
Sender: news@csus.edu
Organization: San Francisco State University
Distribution: NA
Date: Thu, 11 Jun 1992 21:15:13 GMT
Lines: 47

Simple J questions.

    If a=. i.3 4  How do I ...

1.  Insert a zero row in (new rows) 0 and 3
    0  0  0  0
    0  1  2  3
    4  5  6  7
    0  0  0  0
    8  9 10 11
 
2. Insert a zero column  in ( new columns ) 0 and 3
    0   1  2  0   3 
    4   5  6  0   7
    8   9 10  0  11

3. Annihilate row 1 to get
    0  1  2  3
    8  9 10 11

4. Annihilate column 2 to get
   0  1  3
   4  5  7
   8  9 11
---------------------------------

    If a =. 4 4 $  0 
       b =. 2 2 $  >: i.4
       c =. 10  *  >: i. 2 4
       d=. 1 2 3 4

5. Create, using a,b,c and d only ,

     0 0 0 0    0 0 0 0    0  0  0  0    10  0 50 0   0 0 0 0  0 0 1 0
     0 1 2 0    0 0 0 0   10 20 30 40    20  0 60 0   0 0 0 0  0 0 2 0
     0 3 4 0    0 0 1 2    0  0  0  0    30  0 70 0   1 2 3 4  0 0 3 0
     0 0 0 0    0 0 3 4   50 60 70 80    40  0 80 0   0 0 0 0  0 0 4 0

 6. I would like to see a simple example using UNTIL
    as described in the dictionary on the bottom of page 15 .
    I find the explanation to complicated.
    What is the meaning of (1 _1) ? In this context?

Thanks!!

    Emmett 
    vpcsc4@sfsuvax1.sfsu.edu
