85 lines
1.8 KiB
JavaScript
85 lines
1.8 KiB
JavaScript
/**
|
|
* @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' );
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Computes the range of a double-precision floating-point strided array.
|
|
*
|
|
* @param {PositiveInteger} N - number of indexed elements
|
|
* @param {Float64Array} x - input array
|
|
* @param {integer} stride - stride length
|
|
* @param {NonNegativeInteger} offset - starting index
|
|
* @returns {number} range
|
|
*
|
|
* @example
|
|
* var Float64Array = require( '@stdlib/array/float64' );
|
|
* var floor = require( '@stdlib/math/base/special/floor' );
|
|
*
|
|
* var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
|
|
* var N = floor( x.length / 2 );
|
|
*
|
|
* var v = drange( N, x, 2, 1 );
|
|
* // returns 6.0
|
|
*/
|
|
function drange( N, x, stride, offset ) {
|
|
var max;
|
|
var min;
|
|
var ix;
|
|
var v;
|
|
var i;
|
|
|
|
if ( N <= 0 ) {
|
|
return NaN;
|
|
}
|
|
if ( N === 1 || stride === 0 ) {
|
|
if ( isnan( x[ offset ] ) ) {
|
|
return NaN;
|
|
}
|
|
return 0.0;
|
|
}
|
|
ix = offset;
|
|
min = x[ ix ];
|
|
max = min;
|
|
for ( i = 1; i < N; i++ ) {
|
|
ix += stride;
|
|
v = x[ ix ];
|
|
if ( isnan( v ) ) {
|
|
return v;
|
|
}
|
|
if ( v < min ) {
|
|
min = v;
|
|
} else if ( v > max ) {
|
|
max = v;
|
|
}
|
|
}
|
|
return max - min;
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = drange;
|