text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2020 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 abs = require( '@stdlib/math/base/special/abs' );
  
  
  // MAIN //
  
  /**
  * Adds a constant to each strided array element and computes the sum using an improved Kahan–Babuška algorithm.
  *
  * ## Method
  *
  * -   This implementation uses an "improved Kahan–Babuška algorithm", as described by Neumaier (1974).
  *
  * ## References
  *
  * -   Neumaier, Arnold. 1974. "Rounding Error Analysis of Some Methods for Summing Finite Sums." _Zeitschrift Für Angewandte Mathematik Und Mechanik_ 54 (1): 39–51. doi:[10.1002/zamm.19740540106](https://doi.org/10.1002/zamm.19740540106).
  *
  * @param {PositiveInteger} N - number of indexed elements
  * @param {number} alpha - constant
  * @param {NumericArray} x - input array
  * @param {integer} stride - stride length
  * @param {NonNegativeInteger} offset - starting index
  * @returns {number} sum
  *
  * @example
  * var floor = require( '@stdlib/math/base/special/floor' );
  *
  * var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ];
  * var N = floor( x.length / 2 );
  *
  * var v = gapxsumkbn( N, 5.0, x, 2, 1 );
  * // returns 25.0
  */
  function gapxsumkbn( N, alpha, x, stride, offset ) {
  	var sum;
  	var ix;
  	var v;
  	var t;
  	var c;
  	var i;
  
  	if ( N <= 0 ) {
  		return 0.0;
  	}
  	if ( N === 1 || stride === 0 ) {
  		return alpha + x[ offset ];
  	}
  	ix = offset;
  	sum = 0.0;
  	c = 0.0;
  	for ( i = 0; i < N; i++ ) {
  		v = alpha + x[ ix ];
  		t = sum + v;
  		if ( abs( sum ) >= abs( v ) ) {
  			c += (sum-t) + v;
  		} else {
  			c += (v-t) + sum;
  		}
  		sum = t;
  		ix += stride;
  	}
  	return sum + c;
  }
  
  
  // EXPORTS //
  
  module.exports = gapxsumkbn;
  