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 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 PINF = require( '@stdlib/constants-float64-pinf' );
  var NINF = require( '@stdlib/constants-float64-ninf' );
  
  
  // MAIN //
  
  /**
  * Evaluates the natural logarithm of the probability density function (logPDF) for a beta distribution with first shape parameter `alpha` and second shape parameter `beta` at a value `x`.
  *
  * @param {number} x - input value
  * @param {PositiveNumber} alpha - first shape parameter
  * @param {PositiveNumber} beta - second shape parameter
  * @returns {number} evaluated logPDF
  *
  * @example
  * var y = logpdf( 0.5, 1.0, 1.0 );
  * // returns 0.0
  *
  * @example
  * var y = logpdf( 0.5, 2.0, 4.0 );
  * // returns ~0.223
  *
  * @example
  * var y = logpdf( 0.2, 2.0, 2.0 );
  * // returns ~-0.041
  *
  * @example
  * var y = logpdf( 0.8, 4.0, 4.0 );
  * // returns ~-0.556
  *
  * @example
  * var y = logpdf( -0.5, 4.0, 2.0 );
  * // returns -Infinity
  *
  * @example
  * var y = logpdf( 1.5, 4.0, 2.0 );
  * // returns -Infinity
  *
  * @example
  * var y = logpdf( 0.5, -1.0, 0.5 );
  * // returns NaN
  *
  * @example
  * var y = logpdf( 0.5, 0.5, -1.0 );
  * // returns NaN
  *
  * @example
  * var y = logpdf( NaN, 1.0, 1.0 );
  * // returns NaN
  *
  * @example
  * var y = logpdf( 0.5, NaN, 1.0 );
  * // returns NaN
  *
  * @example
  * var y = logpdf( 0.5, 1.0, NaN );
  * // returns NaN
  */
  function logpdf( x, alpha, beta ) {
  	var out;
  	if (
  		isnan( x ) ||
  		isnan( alpha ) ||
  		isnan( beta ) ||
  		alpha <= 0.0 ||
  		beta <= 0.0
  	) {
  		return NaN;
  	}
  	if ( x < 0.0 || x > 1.0 ) {
  		// Support of the Beta distribution: [0,1]
  		return NINF;
  	}
  	if ( x === 0.0 ) {
  		if ( alpha < 1.0 ) {
  			return PINF;
  		}
  		if ( alpha > 1.0 ) {
  			return NINF;
  		}
  		return ln( beta );
  	}
  	if ( x === 1.0 ) {
  		if ( beta < 1.0 ) {
  			return PINF;
  		}
  		if ( beta > 1.0 ) {
  			return NINF;
  		}
  		return ln( alpha );
  	}
  	out = ( alpha-1.0 ) * ln( x );
  	out += ( beta-1.0 ) * log1p( -x );
  	out -= betaln( alpha, beta );
  	return out;
  }
  
  
  // EXPORTS //
  
  module.exports = logpdf;
  