* y (Signum)
The Sign of numeric noun: y, viz:
1 if y>0
0 if y=0
_1 if y<0
This following is an animation for the Signum monadic verb that might be useful to those new to J
Common uses
To locate negative elements in an array for special treatment
] z=: 10 - ?6 6 $ 20 7 _6 5 7 10 _7 _5 2 1 6 6 0 _3 _8 _1 6 _1 _9 3 _2 5 3 3 _7 _1 _5 5 _8 _3 0 _1 _4 6 9 _6 _4 *z 1 _1 1 1 1 _1 _1 1 1 1 1 0 _1 _1 _1 1 _1 _1 1 _1 1 1 1 _1 _1 _1 1 _1 _1 0 _1 _1 1 1 _1 _1
See Also
x * y (Times)
The product of two numeric nouns, x and y .
5 * 7 35 z */ z=. >: i.10 NB. multiplication table 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 5 10 15 20 25 30 35 40 45 50 6 12 18 24 30 36 42 48 54 60 7 14 21 28 35 42 49 56 63 70 8 16 24 32 40 48 56 64 72 80 9 18 27 36 45 54 63 72 81 90 10 20 30 40 50 60 70 80 90 100
Common uses
To multiply two numeric quantities
100 * 0 1 2 0 100 200
To multiply together the entries of a numeric vector
*/2 3 4 24
See Also
Vocabulary/percent (division)