Logarithm of Probability Mass Function

Evaluate the natural logarithm of the probability mass function (PMF) for a degenerate distribution.

Installation

npm install @stdlib/stats-base-dists-degenerate-logpmf

Usage

var logpmf = require( '@stdlib/stats-base-dists-degenerate-logpmf' );

logpmf( x, mu )

Evaluates the natural logarithm of the PMF for a degenerate distribution centered at mu.

var y = logpmf( 2.0, 8.0 );
// returns -Infinity

y = logpmf( 8.0, 8.0 );
// returns 0.0

logpmf.factory( mu )

Returns a function for evaluating the natural logarithm of the PMF of a degenerate distribution centered at mu.

var mylogpmf = logpmf.factory( 10.0 );

var y = mylogpmf( 10.0 );
// returns 0.0

y = mylogpmf( 5.0 );
// returns -Infinity

y = mylogpmf( 12.0 );
// returns -Infinity

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var logpmf = require( '@stdlib/stats-base-dists-degenerate-logpmf' );

var opts = {
    'dtype': 'float64'
};
var x = discreteUniform( 100, 0, 5, opts );
var mu = discreteUniform( 100, 0, 5, opts );

logEachMap( 'x: %d, µ: %d, ln(P(X=x;µ)): %0.4f', x, mu, logpmf );

C APIs

Usage

#include "stdlib/stats/base/dists/degenerate/logpmf.h"

stdlib_base_dists_degenerate_logpmf( x, mu )

Evaluates the natural logarithm of the probability mass function (PMF) for a degenerate distribution.

double out = stdlib_base_dists_degenerate_logpmf( 2.0, 3.0 );
// returns -Infinity

The function accepts the following arguments:

• x: [in] double input value.
• mu: [in] double constant value of the distribution.

double stdlib_base_dists_degenerate_logpmf( const double x, const double mu );

Examples

#include "stdlib/stats/base/dists/degenerate/logpmf.h"
#include "stdlib/math/base/special/round.h"
#include <stdlib.h>
#include <stdio.h>

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 result;
    double mu;
    double x;
    int i;

    for ( i = 0; i < 10; i++ ) {
        x = stdlib_base_round( random_uniform( 0.0, 5.0 ) );
        mu = stdlib_base_round( random_uniform( 0.0, 5.0 ) );
        result = stdlib_base_dists_degenerate_logpmf( x, mu );
        printf( "x: %lf, µ: %lf, ln(P(X=x;µ)): %lf \n", x, mu, result );
    }
}

Notice

This package is part of 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, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.