88 lines
2.3 KiB
JavaScript
88 lines
2.3 KiB
JavaScript
|
/**
|
||
|
|
* @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 pow = require( '@stdlib/math/base/special/pow' );
|
||
|
|
var isNumber = require( '@stdlib/assert/is-number' ).isPrimitive;
|
||
|
|
var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
|
||
|
|
var isnan = require( '@stdlib/math/base/assert/is-nan' );
|
||
|
|
|
||
|
|
|
||
|
|
// MAIN //
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Generates a logarithmically spaced numeric array.
|
||
|
|
*
|
||
|
|
* @param {number} a - exponent of start value
|
||
|
|
* @param {number} b - exponent of end value
|
||
|
|
* @param {NonNegativeInteger} [len=10] - length of output array
|
||
|
|
* @throws {TypeError} first argument must be numeric
|
||
|
|
* @throws {TypeError} second argument must be numeric
|
||
|
|
* @throws {TypeError} third argument must be a nonnegative integer
|
||
|
|
* @returns {Array} logarithmically spaced numeric array
|
||
|
|
*
|
||
|
|
* @example
|
||
|
|
* var arr = logspace( 0, 2, 6 );
|
||
|
|
* // returns [ 1, ~2.5, ~6.31, ~15.85, ~39.81, 100 ]
|
||
|
|
*/
|
||
|
|
function logspace( a, b, len ) {
|
||
|
|
var arr;
|
||
|
|
var end;
|
||
|
|
var tmp;
|
||
|
|
var d;
|
||
|
|
var i;
|
||
|
|
if ( !isNumber( a ) || isnan( a ) ) {
|
||
|
|
throw new TypeError( 'invalid argument. Exponent of start value must be numeric. Value: `' + a + '`.' );
|
||
|
|
}
|
||
|
|
if ( !isNumber( b ) || isnan( b ) ) {
|
||
|
|
throw new TypeError( 'invalid argument. Exponent of stop value must be numeric. Value: `' + b + '`.' );
|
||
|
|
}
|
||
|
|
if ( arguments.length < 3 ) {
|
||
|
|
len = 10;
|
||
|
|
} else {
|
||
|
|
if ( !isNonNegativeInteger( len ) ) {
|
||
|
|
throw new TypeError( 'invalid argument. Length must be a nonnegative integer. Value: `' + len + '`.' );
|
||
|
|
}
|
||
|
|
if ( len === 0 ) {
|
||
|
|
return [];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
// Calculate the increment:
|
||
|
|
end = len - 1;
|
||
|
|
d = ( b-a ) / end;
|
||
|
|
|
||
|
|
// Build the output array...
|
||
|
|
arr = [];
|
||
|
|
tmp = a;
|
||
|
|
arr.push( pow( 10, tmp ) );
|
||
|
|
for ( i = 1; i < end; i++ ) {
|
||
|
|
tmp += d;
|
||
|
|
arr.push( pow( 10, tmp ) );
|
||
|
|
}
|
||
|
|
arr.push( pow( 10, b ) );
|
||
|
|
return arr;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// EXPORTS //
|
||
|
|
|
||
|
|
module.exports = logspace;
|