A+ employs 0-origin indexing

when using firefox to view text pages about aplus use
monospace font KAPL and ISO 8859-1 encoding

when editing this file aplus-notes.txt use kedit
with KAPL font and iso 8859-1 encoding

xmodmap usapl.txt    necessary to get the alt key to work as expected

export LANG=en_GB.iso8859    this may be necessary for scripts
export LC_ALL=ISO-8859-1     this may be necessary for scripts

! for factorial is not implemented

system variable names begin with `.

examples in ~/Downloads/aplus-fsf-4.22/src/a

alt shift c generates the comment character, everything on that line is a comment
alt shift 4 generates the sort symbol
alt shift 5 gives circle with vertical line
alt shift f gives depth 
alt shift 8 gives natural log
alt 2       generates high minus
alt =       generates divide 
alt [       gives <- operator
alt ]       gives -> operator (clears error, $ also clears error)
alt -       gives multiply
alt =       gives divide
alt s       gives ceiling
alt d       gives floor
alt `       gives diamond
alt q       gives ?
alt l       gives box
alt o       gives pi times
alt r       gives reshape 

$load s    loads screen management facilities

operating system commands in general can be accessed by preceeding
the $ symbol before it:

$date
$time

in other versions of APL the box symbol is used for built-in
variables, but in aplus $ is used instead:

$pp         returns the number of digits of precision which is 10

$mode       returns current mode (e.g. apl or ascii or uni)
$off        logs out of aplus
$vars       returns all the variables
$sfs        returns system function names
$si         state indicator
$vers       returns version of aplus
$reset      reset all suspensions
$mode ascii 
            set ascii mode

$cx c       switch to context c
$cx .       return to root context

É10         returns the numbers 0 to 9

3 3 Ғɉ9
            returns the numbers 0 to 8 in a 3x3 matrix

a <- 'gerbie power'
#a          returns the number of characters or 12

a <- 'apple'
b <- 'pear'
c <- a,b    stores applepear in c

square x: x*.5
$fns        returns that square is a function

square 1 4 9 16
            returns 1 2 3 4

?3          returns a random number from 0 to 2

100 ? 100   generates 100 random numbers from 0 to 99

12/4        generate 12 4's

table û 3 3 Ò 1 2 3 4 5 6 7 8 9
table[2;2]  returns 9
Ã’           returns 3 3

c.b <- 'abcdef'
            store abcdef in b in the context of c

%`a         display a in the root context
%`c.b       display b in the c context

xûÉ3 5 6    create 3 dimension array x
x[0;0;0]û50 set the element at coordinates (0,0,0) to 50

aûÉ3 4      create 3x4 array with elements 0 to 11
a[]û5       set all elements of array to 5

a û 1 2 3
a[,] û 4    append 4 to array a

5ß(Õ2)      Õ is generated by alt-u

1 2 3 Ê.+ 4 5 6
            outer product of +
         + �  4  5  6
	---�---------
	 1 �  5  6  7
	 2 �  6  7  8
	 3 �  7  8  9
	
v û 1 2 3 4 5
v[0 1 4]    returns 1 2 5

nû10
xûn do Õn   returns numbers 0 to 9

xû(nû10) do Õn
            same thing on one line

vû 53 14 27 2 31 85 30 11 67 50
	gû`v
	show `g is `graph
            display graph of g
`g has (`title;"Graph Tutorial Example")
            give graph a title

functions
---------

n test t:{
a <- 10;
b <- 20;
c ,<- a + b;
c;
t}