iterSquareWave

Create an iterator which generates a square wave.

A square waveform is represented by the following equation

f left-parenthesis t semicolon tau comma a Subscript min Baseline comma a Subscript max Baseline comma phi right-parenthesis equals StartLayout Enlarged left-brace 1st Row 1st Column a Subscript max Baseline 2nd Column left-parenthesis t minus phi right-parenthesis mod left-parenthesis tau slash 2 right-parenthesis 2nd Row 1st Column a Subscript min Baseline 2nd Column otherwise EndLayout

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

Usage

var iterSquareWave = require( '@stdlib/simulate/iter/square-wave' );

iterSquareWave( [options] )

Returns an iterator which generates a square wave.

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

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

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

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

// ...

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 square wave repeats). This must be an even integer in order to ensure a 50% duty cycle. Default: 10.
  • min: minimum amplitude. Default: -1.0.
  • max: maximum 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 square wave that repeats every 10 iterations. To specify an alternative period, set the period option.

var opts = {
    'period': 4
};

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

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

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

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

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

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': 6,
    'offset': -2
};

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

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

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

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

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

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

// ...

To translate the waveform to the right,

var opts = {
    'period': 6,
    'offset': 2
};

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

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

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

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

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

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

// ...

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 = iterSquareWave( opts );
// returns <Object>

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

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

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

Notes

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

Examples

var iterSquareWave = require( '@stdlib/simulate/iter/square-wave' );

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

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