Hi Ric,

I have to admit that I'm new to this type of programming with J so
please be patient with my questions.
1. I initially tried doing a tacit definition of
   cmp0=: I. 0 =
|syntax error
|   cmp0=:    I.0=
So why does the following script not fail anymore (although it doesn't
work)?
   cmp0=: I. 0 =,

2. M is 2 dimension matrix. The result of ([: I. 0 = ,@]) is 6 and 8.
The code proceeded to amend the data as if it was a vector!!! If I try
to do that manually, I'll get errors. Why? I've always thought that in a
2 dimension matrix, I need to provide the row and column position for
amends
   _ 6} M
|domain error
|       _&6}M
   _ (6}) M
|length error
|       _ 6}M
   _& (6}) M
|index error
|   _    (6})M
   _ 6} M
|index error
|       _&(6})M
   _ (6)} M
|length error
|       _ 6}M
   _ (6)} M
|index error
|   _    (6)}M

3. This is the first time I use [: symbol. I looked it up in the help
file and my brains threw a breaker after reading this :
"For example, 5(+*-)3 is (5+3)*(5-3). If f is a cap ([:) the capped
branch simplifies the forks to g h y and g x h y . The train N g h (a
noun followed by two verbs) is equivalent to N"_ g h . The ranks of the
hook and fork are infinite." 
I would appreciate it if somebody can provide a better explanation ...
please. :)

Thanks.

r/Alex

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Sherlock, Ric
Sent: Thursday, September 18, 2008 5:20 PM
To: Programming forum
Subject: [Jprogramming] RE: Applying Amend on each row

---Alex Rufon wrote:
> What I want to do is to replace all zero in the matrix with infinity.

   ]M=: 4 [EMAIL PROTECTED]
6 5 9 2
4 9 0 7
0 4 6 8
3 8 1 2

amendZeros=: _&(([: I. 0 = ,@])})

   amendZeros M
6 5 9 2
4 9 _ 7
_ 4 6 8
3 8 1 2

Check out Chapter 6.3.3 Linear Indices in Learning J

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