iterCosineWave

Create an iterator which generates a cosine wave.

A cosine waveform is represented by the following equation

where τ is the period, a is the peak amplitude, and φ is the phase offset.

Installation

npm install @stdlib/simulate-iter-cosine-wave

Usage

var iterCosineWave = require( '@stdlib/simulate-iter-cosine-wave' );

iterCosineWave( [options] )

Returns an iterator which generates a cosine wave.

var it = iterCosineWave();
// returns <Object>

var v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

// ...

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.

The function supports the following options:

• period: period (i.e., the number of iterations before a cosine wave repeats). Default: 10.
• amplitude: peak amplitude. Default: 1.0.
• offset: phase offset (in units of iterations; zero-based). A negative offset translates a waveform to the left. A positive offset translates a waveform to the right. Default: 0.
• iter: number of iterations. Default: 1e308.

By default, the function returns an iterator which generates a cosine wave that repeats every 10 iterations. To specify an alternative period, set the period option.

var opts = {
    'period': 4
};

var it = iterCosineWave( opts );
// returns <Object>

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

v = it.next().value;
// returns 0.0

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

v = it.next().value;
// returns 0.0

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

// ...

To adjust at what point the iterator begins in the waveform cycle, set the phase offset option. For example, to translate the waveform to the left,

var opts = {
    'period': 4,
    'offset': -1
};

var it = iterCosineWave( opts );
// returns <Object>

var v = it.next().value;
// returns 0.0

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

v = it.next().value;
// returns 0.0

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

v = it.next().value;
// returns 0.0

// ...

To translate the waveform to the right,

var opts = {
    'period': 4,
    'offset': 1
};

var it = iterCosineWave( opts );
// returns <Object>

var v = it.next().value;
// returns 0.0

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

v = it.next().value;
// returns 0.0

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

v = it.next().value;
// returns 0.0

// ...

By default, the function returns an infinite iterator (i.e., an iterator which never ends). To limit the number of iterations, set the iter option.

var opts = {
    'iter': 2
};
var it = iterCosineWave( opts );
// returns <Object>

var v = it.next().value;
// returns <number>

v = it.next().value;
// returns <number>

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

Notes

• If an environment supports Symbol.iterator, the returned iterator is iterable.

Examples

var iterCosineWave = require( '@stdlib/simulate-iter-cosine-wave' );

// Create an iterator:
var opts = {
    'period': 10,
    'amplitude': 10.0,
    'offset': -5,
    'iter': 100
};
var it = iterCosineWave( opts );

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

See Also

• @stdlib/simulate-iter/pulse: create an iterator which generates a pulse waveform.
• @stdlib/simulate-iter/sawtooth-wave: create an iterator which generates a sawtooth wave.
• @stdlib/simulate-iter/sine-wave: create an iterator which generates a sine wave.
• @stdlib/simulate-iter/square-wave: create an iterator which generates a square wave.
• @stdlib/simulate-iter/triangle-wave: create an iterator which generates a triangle wave.

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.