feat: add C implementation for @stdlib/stats/base/dists/erlang/logpdf

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

@@ -0,0 +1,76 @@
+/**
+* @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 resolve = require( 'path' ).resolve;
+var bench = require( '@stdlib/bench' );
+var Float64Array = require( '@stdlib/array/float64' );
+var uniform = require( '@stdlib/random/base/uniform' );
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var EPS = require( '@stdlib/constants/float64/eps' );
+var tryRequire = require( '@stdlib/utils/try-require' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+
+
+// VARIABLES //
+
+var logpdf = tryRequire( resolve( __dirname, './../lib/native.js' ) );
+var opts = {
+	'skip': ( logpdf instanceof Error )
+};
+
+
+// MAIN //
+
+bench( format( '%s::native', pkg ), opts, function benchmark( b ) {
+	var lambda;
+	var len;
+	var k;
+	var x;
+	var y;
+	var i;
+
+	len = 100;
+	x = new Float64Array( len );
+	k = new Float64Array( len );
+	lambda = new Float64Array( len );
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = uniform( EPS, 50.0 );
+		k[ i ] = discreteUniform( 1, 10 );
+		lambda[ i ] = uniform( EPS, 20.0 );
+	}
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = logpdf( x[ i % len ], k[ i % len ], lambda[ i % len ] );
+		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();
+} );

lib/node_modules/@stdlib/stats/base/dists/erlang/logpdf/include/stdlib/stats/base/dists/erlang/logpdf.h

@@ -0,0 +1,35 @@
+/**
+* @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.
+*/
+
+#ifndef STDLIB_STATS_BASE_DISTS_ERLANG_LOGPDF_H
+#define STDLIB_STATS_BASE_DISTS_ERLANG_LOGPDF_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+* Evaluates the natural logarithm of the probability density function (PDF) for an Erlang distribution with shape parameter `k` and rate parameter `lambda`.
+*/
+double stdlib_base_dists_erlang_logpdf( const double x, const double k, const double lambda );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // !STDLIB_STATS_BASE_DISTS_ERLANG_LOGPDF_H

lib/node_modules/@stdlib/stats/base/dists/erlang/logpdf/lib/native.js

@@ -0,0 +1,48 @@
+/**
+* @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 addon = require( './../src/addon.node' );
+
+
+// MAIN //
+
+/**
+* Evaluates the natural logarithm of the probability density function (PDF) for an Erlang distribution with shape parameter `k` and rate parameter `lambda` at a value `x`.
+*
+* @private
+* @param {number} x - input value
+* @param {NonNegativeInteger} k - shape parameter
+* @param {PositiveNumber} lambda - rate parameter
+* @returns {number} evaluated logPDF
+*
+* @example
+* var y = logpdf( 0.1, 1, 1.0 );
+* // returns ~-0.1
+*/
+function logpdf( x, k, lambda ) {
+	return addon( x, k, lambda );
+}
+
+
+// EXPORTS //
+
+module.exports = logpdf;

lib/node_modules/@stdlib/stats/base/dists/erlang/logpdf/manifest.json

@@ -0,0 +1,89 @@
+{
+  "options": {
+    "task": "build",
+    "wasm": false
+  },
+  "fields": [
+    {
+      "field": "src",
+      "resolve": true,
+      "relative": true
+    },
+    {
+      "field": "include",
+      "resolve": true,
+      "relative": true
+    },
+    {
+      "field": "libraries",
+      "resolve": false,
+      "relative": false
+    },
+    {
+      "field": "libpath",
+      "resolve": true,
+      "relative": false
+    }
+  ],
+  "confs": [
+    {
+      "task": "build",
+      "wasm": false,
+      "src": [
+        "./src/main.c"
+      ],
+      "include": [
+        "./include"
+      ],
+      "libraries": [],
+      "libpath": [],
+      "dependencies": [
+        "@stdlib/math/base/napi/ternary",
+        "@stdlib/math/base/assert/is-nonnegative-integer",
+        "@stdlib/math/base/assert/is-nan",
+        "@stdlib/stats/base/dists/gamma/logpdf",
+        "@stdlib/constants/float64/ninf",
+        "@stdlib/constants/float64/pinf"
+      ]
+    },
+    {
+      "task": "benchmark",
+      "wasm": false,
+      "src": [
+        "./src/main.c"
+      ],
+      "include": [
+        "./include"
+      ],
+      "libraries": [],
+      "libpath": [],
+      "dependencies": [
+        "@stdlib/math/base/assert/is-nonnegative-integer",
+        "@stdlib/math/base/assert/is-nan",
+        "@stdlib/stats/base/dists/gamma/logpdf",
+        "@stdlib/constants/float64/ninf",
+        "@stdlib/constants/float64/pinf",
+        "@stdlib/constants/float64/eps"
+      ]
+    },
+    {
+      "task": "examples",
+      "wasm": false,
+      "src": [
+        "./src/main.c"
+      ],
+      "include": [
+        "./include"
+      ],
+      "libraries": [],
+      "libpath": [],
+      "dependencies": [
+        "@stdlib/math/base/assert/is-nonnegative-integer",
+        "@stdlib/math/base/assert/is-nan",
+        "@stdlib/stats/base/dists/gamma/logpdf",
+        "@stdlib/constants/float64/ninf",
+        "@stdlib/constants/float64/pinf"
+      ]
+    }
+  ]
+}

lib/node_modules/@stdlib/stats/base/dists/erlang/logpdf/package.json

@@ -18,7 +18,9 @@
     "benchmark": "./benchmark",
     "doc": "./docs",
     "example": "./examples",
+    "include": "./include",
     "lib": "./lib",
+    "src": "./src",
     "test": "./test"
   },
   "types": "./docs/types",

lib/node_modules/@stdlib/stats/base/dists/erlang/logpdf/src/addon.c

@@ -0,0 +1,22 @@
+/**
+* @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.
+*/
+
+#include "stdlib/stats/base/dists/erlang/logpdf.h"
+#include "stdlib/math/base/napi/ternary.h"
+
+STDLIB_MATH_BASE_NAPI_MODULE_DDD_D( stdlib_base_dists_erlang_logpdf )

lib/node_modules/@stdlib/stats/base/dists/erlang/logpdf/src/main.c

@@ -0,0 +1,51 @@
+/**
+* @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.
+*/
+
+#include "stdlib/stats/base/dists/erlang/logpdf.h"
+#include "stdlib/stats/base/dists/gamma/logpdf.h"
+#include "stdlib/math/base/assert/is_nonnegative_integer.h"
+#include "stdlib/math/base/assert/is_nan.h"
+#include "stdlib/constants/float64/ninf.h"
+#include "stdlib/constants/float64/pinf.h"
+
+/**
+* Evaluates the natural logarithm of the probability density function (PDF) for an Erlang distribution with shape parameter `k` and rate parameter `lambda` at a value `x`.
+*
+* @param x       input value
+* @param k       shape parameter (must be a nonnegative integer)
+* @param lambda  rate parameter (must be positive)
+* @return        evaluated logPDF
+*
+* @example
+* double v = stdlib_base_dists_erlang_logpdf( 0.1, 1, 1.0 );
+* // returns ~-0.1
+*/
+double stdlib_base_dists_erlang_logpdf( const double x, const double k, const double lambda ) {
+	if (
+		stdlib_base_is_nan( x ) ||
+		!stdlib_base_is_nonnegative_integer( k ) ||
+		stdlib_base_is_nan( lambda ) ||
+		lambda <= 0.0
+	) {
+		return 0.0 / 0.0; // NaN
+	}
+	if ( k == 0.0 ) {
+		return ( x == 0.0 ) ? STDLIB_CONSTANT_FLOAT64_PINF : STDLIB_CONSTANT_FLOAT64_NINF;
+	}
+	return stdlib_base_dists_gamma_logpdf( x, k, lambda );
+}