text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2018 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 constantFunction = require( '@stdlib/utils-constant-function' );
  var betaln = require( '@stdlib/math-base-special-betaln' );
  var isnan = require( '@stdlib/math-base-assert-is-nan' );
  var log1p = require( '@stdlib/math-base-special-log1p' );
  var ln = require( '@stdlib/math-base-special-ln' );
  var NINF = require( '@stdlib/constants-float64-ninf' );
  
  
  // MAIN //
  
  /**
  * Returns a function for evaluating the natural logarithm of the probability density function (logPDF) for a beta prime distribution with first shape parameter `alpha` and second shape parameter `beta`.
  *
  * @param {PositiveNumber} alpha - first shape parameter
  * @param {PositiveNumber} beta - second shape parameter
  * @returns {Function} logPDF
  *
  * @example
  * var logpdf = factory( 0.5, 0.5 );
  *
  * var y = logpdf( 0.8 );
  * // returns ~-1.62
  *
  * y = logpdf( 0.3 );
  * // returns ~-0.805
  */
  function factory( alpha, beta ) {
  	var betalnAB;
  	if (
  		isnan( alpha ) ||
  		isnan( beta ) ||
  		alpha <= 0.0 ||
  		beta <= 0.0
  	) {
  		return constantFunction( NaN );
  	}
  	betalnAB = betaln( alpha, beta );
  	return logpdf;
  
  	/**
  	* Evaluates the natural logarithm of the probability density function (PDF) for a beta prime distribution.
  	*
  	* @private
  	* @param {number} x - input value
  	* @returns {number} evaluated natural logarithm of the PDF
  	*
  	* @example
  	* var y = logpdf( 0.3 );
  	* // returns <number>
  	*/
  	function logpdf( x ) {
  		var out;
  		if ( isnan( x ) ) {
  			return NaN;
  		}
  		if ( x <= 0.0 ) {
  			// Support of the BetaPrime distribution: (0,∞)
  			return NINF;
  		}
  		out = ( alpha-1.0 ) * ln( x );
  		out -= ( alpha+beta ) * log1p( x );
  		out -= betalnAB;
  		return out;
  	}
  }
  
  
  // EXPORTS //
  
  module.exports = factory;
  