time-to-botec/squiggle/node_modules/@stdlib/stats/incr/meanabs2/README.md

incrmeanabs2

Compute an arithmetic mean of squared absolute values incrementally.

The arithmetic mean of squared absolute values is defined as

Usage

var incrmeanabs2 = require( '@stdlib/stats/incr/meanabs2' );

incrmeanabs2()

Returns an accumulator function which incrementally computes an arithmetic mean of squared absolute values.

var accumulator = incrmeanabs2();

accumulator( [x] )

If provided an input value x, the accumulator function returns an updated mean. If not provided an input value x, the accumulator function returns the current mean.

var accumulator = incrmeanabs2();

var m = accumulator( 2.0 );
// returns 4.0

m = accumulator( -1.0 );
// returns 2.5

m = accumulator( -3.0 );
// returns ~4.67

m = accumulator();
// returns ~4.67

Notes

• Input values are not type checked. If provided NaN or a value which, when used in computations, results in NaN, the accumulated value is NaN for all future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly before passing the value to the accumulator function.

Examples

var randu = require( '@stdlib/random/base/randu' );
var incrmeanabs2 = require( '@stdlib/stats/incr/meanabs2' );

var accumulator;
var v;
var i;

// Initialize an accumulator:
accumulator = incrmeanabs2();

// For each simulated datum, update the mean...
for ( i = 0; i < 100; i++ ) {
    v = ( randu()*100.0 ) - 50.0;
    accumulator( v );
}
console.log( accumulator() );