Normal distribution quantile function.
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> [Normal][normal-distribution] distribution [quantile function][quantile-function].
The [quantile function][quantile-function] for a [normal][normal-distribution] random variable is
for 0 <= p <= 1, where µ is the mean and σ is the standard deviation.
``bash`
npm install @stdlib/stats-base-dists-normal-quantile
`javascript`
var quantile = require( '@stdlib/stats-base-dists-normal-quantile' );
#### quantile( p, mu, sigma )
Evaluates the [quantile function][quantile-function] for a [normal][normal-distribution] distribution with parameters mu (mean) and sigma (standard deviation).
`javascript
var y = quantile( 0.5, 0.0, 1.0 );
// returns 0.0
y = quantile( 0.2, 4.0, 2.0 );
// returns ~2.317
`
If provided a probability p outside the interval [0,1], the function returns NaN.
`javascript
var y = quantile( 1.9, 0.0, 1.0 );
// returns NaN
y = quantile( -0.1, 0.0, 1.0 );
// returns NaN
`
If provided NaN as any argument, the function returns NaN.
`javascript
var y = quantile( NaN, 0.0, 1.0 );
// returns NaN
y = quantile( 0.0, NaN, 1.0 );
// returns NaN
y = quantile( 0.0, 0.0, NaN );
// returns NaN
`
If provided sigma < 0, the function returns NaN.
`javascript`
var y = quantile( 0.4, 0.0, -1.0 );
// returns NaN
If provided sigma = 0, the function evaluates the [quantile function][quantile-function] of a [degenerate distribution][degenerate-distribution] centered at mu.
`javascript
var y = quantile( 0.3, 8.0, 0.0 );
// returns 8.0
y = quantile( 0.9, 8.0, 0.0 );
// returns 8.0
`
#### quantile.factory( mu, sigma )
Returns a function for evaluating the [quantile function][quantile-function] of a [normal][normal-distribution] distribution with parameters mu and sigma.
`javascript
var myquantile = quantile.factory( 10.0, 2.0 );
var y = myquantile( 0.2 );
// returns ~8.317
y = myquantile( 0.8 );
// returns ~11.683
`
`javascript
var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var quantile = require( '@stdlib/stats-base-dists-normal-quantile' );
var opts = {
'dtype': 'float64'
};
var sigma = uniform( 10, 0.0, 20.0, opts );
var mu = uniform( 10, -5.0, 5.0, opts );
var p = uniform( 10, 0.0, 1.0, opts );
logEachMap( 'p: %0.4f, µ: %0.4f, σ: %0.4f, Q(p;µ,σ): %0.4f', p, mu, sigma, quantile );
`
*
`c`
#include "stdlib/stats/base/dists/normal/quantile.h"
#### stdlib_base_dists_normal_quantile( p, mu, sigma )
Evaluates the [quantile function][quantile-function] for a [normal][normal-distribution] distribution with parameters mu (mean) and sigma (standard deviation).
`c`
double y = stdlib_base_dists_normal_quantile( 0.8, 0.0, 1.0 );
// returns ~0.842
The function accepts the following arguments:
- p: [in] double probability.[in] double
- mu: mean.[in] double
- sigma: standard deviation.
`c`
double stdlib_base_dists_normal_quantile( const double p, const double mu, const double sigma );
`c
#include "stdlib/stats/base/dists/normal/quantile.h"
#include "stdlib/constants/float64/eps.h"
#include
#include
static double random_uniform( const double min, const double max ) {
double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
return min + ( v*(max-min) );
}
int main( void ) {
double sigma;
double mu;
double p;
double y;
int i;
for ( i = 0; i < 10; i++ ) {
p = random_uniform( 0.0, 1.0 );
mu = random_uniform( -5.0, 5.0 );
sigma = random_uniform( STDLIB_CONSTANT_FLOAT64_EPS, 20.0 );
y = stdlib_base_dists_normal_quantile( p, mu, sigma );
printf( "p:%.4f, µ: %.4f, σ: %.4f, Q(p;µ,σ): %.4f\n", p, mu, sigma, y );
}
}
`
*
This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
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[quantile-function]: https://en.wikipedia.org/wiki/Quantile_function
[normal-distribution]: https://en.wikipedia.org/wiki/Normal_distribution
[degenerate-distribution]: https://en.wikipedia.org/wiki/Degenerate_distribution