Programmer Guide/Command Reference/EVAL/vvget: Difference between revisions

Latest revision as of 19:04, 21 April 2011

Extract elements from a vector.

Usage

vvget(x {, o {, d {,n }}})

Result

A numerical object r (scalar or vector) with n elements

r_i = x_o+i*d; with i=0..n-1

Note: For all i, the source index o+i*d must be in the range 0 to l_x-1, otherwise the function fails.

Example:

#a := eval vv(1,2,4,8,16,32)
#b := eval vvget($#a, 0, 2, 3) 
// → #b = { 1 , 4 , 16 }
#c := eval vvget($#a, 5, -1, 4)
// → #c = { 32, 16, 8, 4 }

@@ Line 1: / Line 1: @@
 {{DISPLAYTITLE:{{SUBPAGENAME}}}}
-=====vvget=====
+Extract elements from a vector.
+;Usage: <code><var>vvget(x</var> {, <var>o</var> {, <var>d</var> {,<var>n</var> }}})</code>
+:;<var>x</var>: the source vector, l<sub>x</sub>=nrow(''x'') must be greater/equal 1
+:;<var>o</var>: the first element to be extracted, 0 &le; ''o'' < l<sub>x</sub> (default='''0''')
+:;<var>d</var>: the index increment (default='''1''')
+:;<var>n</var>: the number of elements to extract, ''n''>0 (default='''l<sub>x</sub>''')
+;Result: A numerical object ''r'' (scalar or vector) with ''n'' elements
+::<code>''r''<sub>i</sub> = x<sub>''o''+i*''d''</sub></code>; with i=0..''n''-1
+:Note: For all i, the source index ''o''+i*''d'' must be in the range 0 to l<sub>x</sub>-1, otherwise the function fails.
+;See also: [[../vv|vv]], [[../vvset|vvset]], [[../vvcat|vvcat]], [[../vmcol|vmcol]], [[../vmrow|vmrow]], [[../vsubn|vsubn]], [[../vsubc|vsubc]]
-{|
+[[../#Functions|<function list>]]
-|-
-|vvget(x, <var>o</var>, <var>d</var>, <var>n</var>)
-|Result: res[i = 0..n-1] = <var>x</var>[<var>o</var> + i*<var>d</var>]
+Example:
-|}
+ #a := eval vv(1,2,4,8,16,32)
+ #b := eval vvget($#a, 0, 2, 3)
+ // &rarr; #b = { 1 , 4 , 16 }
+ #c := eval vvget($#a, 5, -1, 4)
+ // &rarr; #c = { 32, 16, 8, 4 }