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README.md

itercusumabs2

Create an iterator which iteratively computes a cumulative sum of squared absolute values.

The cumulative sum of squared absolute values is defined as

$$\begin{align*} s_0 &= x_0^2 \\ s_1 &= x_1^2 + s_0 \\ s_2 &= x_2^2 + s_1 \\ s_n &= x_n^2 + s_{n-1} = x_n^2 + \sum_{i=0}^{n-1} x_i^2 \end{align*}$$

Usage

var itercusumabs2 = require( '@stdlib/stats/iter/cusumabs2' );

itercusumabs2( iterator )

Returns an iterator which iteratively computes a cumulative sum of squared absolute values.

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

var arr = array2iterator( [ 2.0, 1.0, 3.0, -7.0, -5.0 ] );
var it = itercusumabs2( arr );

var s = it.next().value;
// returns 4.0

s = it.next().value;
// returns 5.0

s = it.next().value;
// returns 14.0

s = it.next().value;
// returns 63.0

s = it.next().value;
// returns 88.0

Notes

  • If an iterated value is non-numeric (including NaN), the function returns NaN for all future iterations. If non-numeric iterated values are possible, you are advised to provide an iterator which type checks and handles non-numeric values accordingly.

Examples

var runif = require( '@stdlib/random/iter/uniform' );
var itercusumabs2 = require( '@stdlib/stats/iter/cusumabs2' );

// Create an iterator for generating uniformly distributed pseudorandom numbers:
var rand = runif( -10.0, 10.0, {
    'seed': 1234,
    'iter': 100
});

// Create an iterator for iteratively computing a cumulative sum of squared absolute values:
var it = itercusumabs2( rand );

// Perform manual iteration...
var v;
while ( true ) {
    v = it.next();
    if ( typeof v.value === 'number' ) {
        console.log( 'sumabs2: %d', v.value );
    }
    if ( v.done ) {
        break;
    }
}

See Also