Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 33x 4x 4x 4x 4x 29x 33x 4x 2x 2x 2x 2x 2x 2x 2x 2x 25x 33x 29x 29x 21x 21x 8x 8x 33x 4x 4x 4x 4x 21x 21x 21x 21x 21x 21x 33x 1x 4x 4x 4x 4x 4x 4x 4x 4x 33x 20x 20x 21x 21x 33x 68x 68x 52x 52x 26x 26x 26x 26x 52x 52x 52x 50x 52x 2x 2x 52x 52x 52x 52x 68x 68x 33x 33x 33x 33x 3x 3x 3x 3x 3x | /**
* @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 isnan = require( '@stdlib/math/base/assert/is-nan' );
var abs = require( '@stdlib/math/base/special/abs' );
// MAIN //
/**
* Computes the sum of double-precision floating-point strided array elements, ignoring `NaN` values and using a second-order iterative Kahan–Babuška algorithm.
*
* ## Method
*
* - This implementation uses a second-order iterative Kahan–Babuška algorithm, as described by Klein (2005).
*
* ## References
*
* - Klein, Andreas. 2005. "A Generalized Kahan-Babuška-Summation-Algorithm." _Computing_ 76 (3): 279–93. doi:[10.1007/s00607-005-0139-x](https://doi.org/10.1007/s00607-005-0139-x).
*
* @param {PositiveInteger} N - number of indexed elements
* @param {Float64Array} x - input array
* @param {integer} strideX - stride length for `x`
* @param {NonNegativeInteger} offsetX - starting index for `x`
* @param {Float64Array} out - output array
* @param {integer} strideOut - stride length for `out`
* @param {NonNegativeInteger} offsetOut - starting index for `out`
* @returns {Float64Array} output array
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
*
* var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN, NaN ] );
* var out = new Float64Array( 2 );
*
* var v = dnannsumkbn2( 5, x, 2, 1, out, 1, 0 );
* // returns <Float64Array>[ 5.0, 4 ]
*/
function dnannsumkbn2( N, x, strideX, offsetX, out, strideOut, offsetOut ) {
var sum;
var ccs;
var flg;
var cs;
var cc;
var ix;
var io;
var v;
var t;
var c;
var n;
var i;
io = offsetOut;
if ( N <= 0 ) {
out[ io ] = 0.0;
out[ io+strideOut ] = 0;
return out;
}
ix = offsetX;
if ( strideX === 0 ) {
if ( isnan( x[ ix ] ) ) {
out[ io ] = 0.0;
out[ io+strideOut ] = 0;
return out;
}
out[ io ] = x[ ix ] * N;
out[ io+strideOut ] = N;
return out;
}
// Find the first non-NaN element...
for ( i = 0; i < N; i++ ) {
v = x[ ix ];
if ( isnan( v ) === false ) {
break;
}
ix += strideX;
}
if ( i === N ) {
out[ io ] = 0.0;
out[ io+strideOut ] = 0;
return out;
}
n = 1;
sum = v;
ix += strideX;
i += 1;
// In order to preserve the sign of zero which can be lost during compensated summation below, find the first non-zero element...
if ( sum === 0.0 ) {
for ( ; i < N; i++ ) {
v = x[ ix ];
if ( isnan( v ) === false ) {
if ( v !== 0.0 ) {
flg = true;
break;
}
sum += v;
n += 1;
}
ix += strideX;
}
} else {
flg = true;
}
ccs = 0.0; // second order correction term for lost low order bits
cs = 0.0; // first order correction term for lost low order bits
for ( ; i < N; i++ ) {
v = x[ ix ];
if ( isnan( v ) === false ) {
t = sum + v;
if ( abs( sum ) >= abs( v ) ) {
c = (sum-t) + v;
} else {
c = (v-t) + sum;
}
sum = t;
t = cs + c;
if ( abs( cs ) >= abs( c ) ) {
cc = (cs-t) + c;
} else {
cc = (c-t) + cs;
}
cs = t;
ccs += cc;
n += 1;
}
ix += strideX;
}
out[ io ] = ( flg ) ? sum+cs+ccs : sum;
out[ io+strideOut ] = n;
return out;
}
// EXPORTS //
module.exports = dnannsumkbn2;
|