iterLog

Create an iterator which iteratively computes the base b logarithm.

Installation

npm install @stdlib/math-iter-special-log

Usage

var iterLog = require( '@stdlib/math-iter-special-log' );

iterLog( x, b )

Returns an iterator which iteratively computes the base b logarithm of x.

var array2iterator = require( '@stdlib/array-to-iterator' );

var x = array2iterator( [ 2.0, 2.0, 10.0 ] );
var y = array2iterator( [ 2.0, 6.0, 2.0 ] );

var it = iterLog( x, y );
// returns <Object>

var r = it.next().value;
// returns 1.0

r = it.next().value;
// returns ~0.3869

r = it.next().value;
// returns ~3.3219

// ...

The returned iterator protocol-compliant object has the following properties:

• next: function which returns an iterator protocol-compliant object containing the next iterated value (if one exists) assigned to a value property and a done property having a boolean value indicating whether the iterator is finished.
• return: function which closes an iterator and returns a single (optional) argument in an iterator protocol-compliant object.

If provided a numeric value as an iterator argument, the value is broadcast as an infinite iterator which always returns the provided value.

var array2iterator = require( '@stdlib/array-to-iterator' );

var x = array2iterator( [ 2.0, 6.0 ] );

var it = iterLog( x, 2.0 );
// returns <Object>

var v = it.next().value;
// returns 1.0

v = it.next().value;
// returns ~2.58496

var bool = it.next().done;
// returns true

Notes

• For negative b or x iterated values, the returned iterator returns NaN.
• If an iterated value is non-numeric (including NaN), the returned iterator returns NaN. If non-numeric iterated values are possible, you are advised to provide an iterator which type checks and handles non-numeric values accordingly.
• The length of the returned iterator is equal to the length of the shortest provided iterator. In other words, the returned iterator ends once one of the provided iterators ends.
• If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

Examples

var uniform = require( '@stdlib/random-iter-uniform' );
var iterLog = require( '@stdlib/math-iter-special-log' );

// Create seeded iterators for generating pseudorandom numbers:
var x = uniform( 0.0, 100.0, {
    'seed': 1234,
    'iter': 10
});

var y = uniform( 0.0, 10.0, {
    'seed': 4567,
    'iter': 10
});

// Create an iterator which consumes the pseudorandom number iterators:
var it = iterLog( x, y );

// Perform manual iteration...
var r;
while ( true ) {
    r = it.next();
    if ( r.done ) {
        break;
    }
    console.log( r.value );
}

See Also

• @stdlib/math-base/special/log: base b logarithm.
• @stdlib/math-iter/special/log10: create an iterator which evaluates the common logarithm (logarithm with base 10) for each iterated value.
• @stdlib/math-iter/special/log1p: create an iterator which evaluates the natural logarithm of 1+x for each iterated value.
• @stdlib/math-iter/special/log2: create an iterator which evaluates the binary logarithm for each iterated value.
• @stdlib/math-iter/special/pow: create an iterator which evaluates the exponential function.

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.