Programmer Guide/Command Reference/EVAL/vvget: Difference between revisions
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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 <= ''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>; 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 failes. | |||
;See also: [[Programmer_Guide/Command_Reference/EVAL/vv|vv]], [[Programmer_Guide/Command_Reference/EVAL/vvset|vvset]], [[Programmer_Guide/Command_Reference/EVAL/vvcat|vvcat]], [[Programmer_Guide/Command_Reference/EVAL/vmcol|vmcol]], [[Programmer_Guide/Command_Reference/EVAL/vmrow|vmrow]], [[Programmer_Guide/Command_Reference/EVAL/vsubn|vsubn]], [[Programmer_Guide/Command_Reference/EVAL/vsubc|vsubc]] | |||
Example: | |||
<pre> | |||
#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 } | |||
</pre> | |||
[[Programmer_Guide/Command_Reference/EVAL#Functions|<function list>]] | |||
{{DISPLAYTITLE:{{SUBPAGENAME}}}} | {{DISPLAYTITLE:{{SUBPAGENAME}}}} | ||
=====vvget===== | =====vvget===== | ||
Revision as of 13:42, 4 April 2011
Extract elements from a vector.
- Usage
vvget(x {, o {, d {,n }}})- x
- the source vector, lx=nrow(x) must be greater/equal 1
- o
- the first element to be extracted, 0 <= o < lx (default=0)
- d
- the index increment (default=1)
- n
- the number of elements to extract, n>0 (default=lx)
- Result
- A numerical object r (scalar or vector) with n elements.
ri = xo+i*d; with i=0..n-1- Note: For all i, the source index o+i*d must be in the range 0 to lx-1, otherwise the function failes.
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 }
vvget
vvget(x, o, d, n)
Result: res[i = 0..n-1] = x[o + i*d]
