install'gtkide'

http://www.jsoftware.com/help/learning/02.htm

ctrl-d          exit
cursor up/down  scroll through history

;               the verb link

=.              local assignment
=:              global assignment

'hello world'	prints hello world
text =. 'hello world'
                store string in text

+/1 2 3         sum the numbers 1 2 3
*/1 2 3         multiply the numbers 1 2 3

4%2             divide 4 by 2

4*2             multiply 4 y 2

5 + 10 20 30    add 5 to 10 20 30

avg=: +/ % #    program to calculate average, e.g. avg 1 2 3 4 5 returns 3

m=: ?. 4 5 $ 50
                create a matrix 4x5 with random numbers

<1 0 0 1 0      boxed data

6!:0 ''         current time
6!:1 ''         seconds since the start of session

v =. green apple dog
                set array v to green apple dog

a =. 1 2 3 4    set array a to 1 2 3 4
a+1             returns 2 3 4 5
a%2             returns 0.5 1 1.5 2

;: '2 + 3'

load 'convert'
   toupper 'testing 1 2 3'

+/i.11          sum the numbers 0 to 10

sum=: +/        assign sum to sum
b =. 1 2 3 4 5
sum b
#b              return number of elements of b (
                # also returns the number of characters in a string

t =. 'text'
~. t            return unique characters of t
sort t          returns the characters of t sorted

i.10            return numbers 0 to 9

2^3             returns 2 to the power of 3

? 20#100        generate 20 random numbers from 0 to 99

0!              zero factorial returns 1
!x: i.5         returns the factorials from 0 to 4 (e.g. 1 1 2 6 24)

scores =: 45 67 89 12 34 55 77 90
/:~scores       sorts scores

6 +. 10         returns greatest common divisor between 6 and 10

v=: ?. 10 $ 10  generate 10 random numbers from 0 to 9

*: 4            calculate square of 4
*: 1 2 3 4      calculate squares of 1 through 4

2 | 7           returns 2 modulo 7 (e.g. 1)

1 + (u =: 99)   assign 99 to u and add 1

table =: 2 3   $   5 6 7  8 9 10
                assign a 2x3 matrix to table
$ table         lists dimensions of table (e.g. 2 3)

gerbil =: 'maximus'
# gerbil        returns 7
gerbil i. 'x'   returns 2

a =: 'The answer is'  ;  42
                a contains The answer is 42 inside a box
0 { a           returns The answer is
1 { a           returns 42

a =: 7
b =: 7
a -: b          -: is match, a matches b so it returns 1

3 3 $ 'xo'      create a 3x3 matrix from characters xo
3 3 $ i.9       create a 3x3 matrix with the numbers 0 to 8
3 3 $ i._9      create a 3x3 matrix with the numbers 8 to 0
a =: 3 3 $ i.9
$ a             returns shape of a which is 3 3 
(< 1 ; 2) { a   returns row 1, column 2 which is 5 in this case

3 >. 5          returns ceiling of 3 and 5 (e.g. 5)
3 <. 5          returns floor of 3 and 5 (e.g. 3)

'a' ,~ 'b'      returns ba

b =: (i.10) +1  b equals the numbers 1 to 10

_1 { a          returns last element of a

s =: 'pasta'
# s             returns 5
z =: 8 {.       pad out s to 8 charactes (with spaces)

|. 'cat'        returns tac

load '~/j701/addons/ide/jhs/demo/jdemo1.ijs'
list

v =: i.10       v contains 0 to 9
p: v            returns first 10 prime numbers