# 2.1.17.8.22.1 y25

## Description

Get the 25th percentile of vector.

## Syntax

double y25( vector & vec )

## Parameters

vec
[input] Origin C vector object

## Return

Returns the 25th percentile of a vector.

## Examples

EX1

// This is a self contained sample program for the function y25,
// Its sample data is created at the beginning of the program.
// To run the program, enter the following command in the Script window:
//   y25_ex1
// It returns like:
//   25th Percentile of Book1_B = 0.248345
void y25_ex1()
{
Worksheet wks;
wks.Create();
Dataset myDs(wks, 1);

//******* Create sample data *****************
myDs.SetSize(8);
myDs=0.3;
myDs=0.097;
myDs=0.41256;
myDs=0.24909;
myDs=0.47304;
myDs=0.2476;
myDs=0.64529;
myDs=0.44514;
myDs.Sort();
//******** End of Sample Data Creation *******

vector vVal = myDs;
double dY25 = y25(vVal);  // Demonstration of y25

printf("25th Percentile of %s = %g\n", myDs.GetName(), dY25);
}

## Remark

Let the $i\,$th percentile be y, set $p=i/100\,$ , n is the number of data points, and let $np=(j+g) \,$

where j is the integer part of np, and g is the fractional part of np, then different methods define the $i^{th}\,$ percentile, y, as described by the following. $y = \begin{cases} \frac 12(x(j)+x(j+1)),& \mbox{if }\ g=0 \\ x_(j+1),& \mbox{if }\ g>0 \end{cases}$

Get the 25th percentile of a vector(Not suppotted Dataset after version 8.0).