colon (:)
Ranging operator. Addresses all elements along an array dimension or of a list.
Description
Colon symbol :
can be used to form implicit
vectors (see also linspace, logspace) :
 j:k
is the vector
[j, j+1,...,k]
(empty ifj>k
); j:d:k
is the vector
[j, j+d, ..., j+m*d]
.
The colon notation can also be used to pick out selected rows, columns and elements of vectors and other arrays (see also extraction, insertion):
 A(:)
is the vector of all the elements of
A
regarded as a single column; A(:,j)
is the
j
th column ofA
; A(i,:)
is the
i
th row ofA
; A(j:k)
is
[A(j),A(j+1),...,A(k)]
; A(:,j:k)
is
if size of[A(1,j) A(1,j+1) ... A(1,k) A(2,j) A(2,j+1) ... A(2,k) . . . . . . . . . . . A(M,j) A(M,j+1) ... A(M,k)]
A
isM
byN
; A(j:k,:)
is
if size of[A(j,1) A(j,2) ... A(j,N) A(j+1,1) A(j+1,2) ... A(j+1,N) . . . . . . . . . . . A(k,1) A(k,2) ... A(k,N)]
A
isM
byN
; A(:)=w
fills the array
A
with entries ofw
(taken column by column ifw
is a 2D array). The amount of entries ofA
must be equal to the amount of entries ofw
.
Please note that even if i
, j
,
k
or d
have a decimal part, only
the integer part will be used.
type(:) is 129.
typeof(:) is "implicitlist" . 
Examples
a = 1:5 b = 1:3:12 A = matrix(1:42,7,6); // vector of all the elements of A A(:) // the jth column of A A(:,j) // the ith row of A A(i,:) // elements of columns from j to k and all rows A(:,j:k) // elements of all columns and rows from j to k A(j:k,:) w = matrix(101:142,7,6); A(:) = w // if indices are not integer i = 1:0.4:10; //indices A(i)
See also
 dollar — ($) last index
 extraction — matrix and list entry extraction
 matrix — reshapes an array with the same number and order of components
 linspace — generates linearly spaced numbers between 2 reached bounds
 logspace — logarithmically spaced vector
History
Version  Description 
6.0 

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