feat: add stats/base/dists/bradford/logpdf

lib/node_modules/@stdlib/stats/base/dists/bradford/logpdf/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2026 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# Logarithm of Probability Density Function
+
+> [Bradford][bradford-distribution] distribution logarithm of the [probability density function][pdf] (logPDF).
+
+<section class="intro">
+
+The logarithm of the [probability density function][pdf] (logPDF) for a [Bradford][bradford-distribution] random variable is
+
+<!-- <equation class="equation" label="eq:bradford_logpdf" align="center" raw="\ln f(x;c)=\ln(c)-\ln(1+cx)-\ln(\ln(1+c))" alt="Logarithm of Probability density function (PDF) for a Bradford distribution."> -->
+
+```math
+\ln f(x;c) = \ln(c) - \ln(1+cx) - \ln(\ln(1+c))
+```
+
+<!-- <div class="equation" align="center" data-raw-text="\ln f(x;c)=\ln(c)-\ln(1+cx)-\ln(\ln(1+c))" data-equation="eq:bradford_pdf">
+<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@51534079fef45e990850102147e8945fb023d1d0/lib/node_modules/@stdlib/stats/base/dists/bradford/pdf/docs/img/equation_bradford_pdf.svg" alt="Probability density function (PDF) for a Bradford distribution.">
+    <br>
+</div> -->
+
+<!-- </equation> -->
+
+where `c > 0` is the shape parameter of the distribution.
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var logpdf = require( '@stdlib/stats/base/dists/bradford/logpdf' );
+```
+
+#### logpdf( x, c )
+
+Evaluates the logarithm of [probability density function][pdf] (PDF) for a [Bradford][bradford-distribution] distribution with shape parameter `c` at a value `x`.
+
+```javascript
+var y = logpdf( 0.1, 0.1 );
+// returns ~0.038
+
+y = logpdf( 0.5, 5.0 );
+// returns ~-0.227
+
+y = logpdf( 1.0, 10.0 );
+// returns ~-0.970
+```
+
+If provided `NaN` as any argument, the function returns `NaN`.
+
+```javascript
+var y = logpdf( NaN, 1.0 );
+// returns NaN
+
+y = logpdf( 0.0, NaN );
+// returns NaN
+```
+
+If provided an `x` value which is outside the support `[0,1]`, the function returns `-Infinity`.
+
+```javascript
+var y = logpdf( 2.0, 1.0 );
+// returns -Infinity
+
+y = logpdf( -0.5, 1.0 );
+// returns -Infinity
+```
+
+If provided a shape parameter `c <= 0`, the function returns `NaN`.
+
+```javascript
+var y = logpdf( 0.5, 0.0 );
+// returns NaN
+
+y = logpdf( 0.5, -5.0 );
+// returns NaN
+```
+
+#### logpdf.factory( c )
+
+Returns a function for evaluating the logarithm of a [PDF][pdf] for a [Bradford][bradford-distribution] distribution with shape parameter `c`.
+
+```javascript
+var myLogPDF = logpdf.factory( 5.0 );
+var y = myLogPDF( 0.5 );
+// returns ~-0.227
+
+y = myLogPDF( 1.0 );
+// returns ~-0.766
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var uniform = require( '@stdlib/random/array/uniform' );
+var logEachMap = require( '@stdlib/console/log-each-map' );
+var logpdf = require( '@stdlib/stats/base/dists/bradford/logpdf' );
+
+var opts = {
+    'dtype': 'float64'
+};
+var c = uniform( 10, 0.1, 10.0, opts );
+var x = uniform( 10, 0.0, 1.0, opts );
+
+logEachMap( 'x: %0.4f, c: %0.4f, ln(f(x;c)): %0.4f', x, c, logpdf );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- C interface documentation. -->
+
+<section class="c">
+
+## C APIs
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/stats/base/dists/bradford/logpdf.h"
+```
+
+#### stdlib_base_dists_bradford_logpdf( x, c )
+
+Evaluates the logarithm of the probability density function for a Bradford distribution.
+
+```c
+double out = stdlib_base_dists_bradford_logpdf( 0.5, 5.0 );
+// returns ~-0.227
+```
+
+The function accepts the following arguments:
+
+-   **x**: `[in] double` input value.
+-   **c**: `[in] double` shape parameter.
+
+```c
+double stdlib_base_dists_bradford_logpdf( const double x, const double c );
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+### Examples
+
+```c
+#include "stdlib/stats/base/dists/bradford/logpdf.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 x;
+    double c;
+    double y;
+    int i;
+
+    for ( i = 0; i < 10; i++ ) {
+        x = random_uniform( 0.0, 1.0 );
+        c = random_uniform( 0.01, 10.0 );
+        y = stdlib_base_dists_bradford_logpdf( x, c );
+        printf( "x: %lf, c: %lf, ln(f(x;c)): %lf\n", x, c, y );
+    }
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+[pdf]: https://en.wikipedia.org/wiki/Probability_density_function
+
+[bradford-distribution]: https://en.wikipedia.org/wiki/Bradford%27s_law
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/stats/base/dists/bradford/logpdf/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var uniform = require( '@stdlib/random/array/uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var logpdf = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var opts;
+	var x;
+	var c;
+	var y;
+	var i;
+
+	opts = {
+		'dtype': 'float64'
+	};
+	x = uniform( 100, 0.0, 1.0, opts );
+	c = uniform( 100, 0.1, 10.0, opts );
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = logpdf( x[ i % x.length ], c[ i % c.length ] );
+		if ( isnan( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+
+	if ( isnan( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( format( '%s:factory', pkg ), function benchmark( b ) {
+	var mylogpdf;
+	var opts;
+	var x;
+	var y;
+	var i;
+
+	opts = {
+		'dtype': 'float64'
+	};
+	x = uniform( 100, 0.0, 1.0, opts );
+	mylogpdf = logpdf.factory( 5.0 );
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = mylogpdf( x[ i % x.length ] );
+		if ( isnan( y ) ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( isnan( y ) ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});