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Promotion Rules

Return the array data type with the smallest size and closest "kind" to which array data types can be safely cast.

Installation

npm install @stdlib/array-promotion-rules

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var promotionRules = require( '@stdlib/array-promotion-rules' );

promotionRules( [dtype1, dtype2] )

If provided data types, returns the array data type with the smallest size and closest "kind" to which array data types can be safely cast.

var out = promotionRules( 'float32', 'uint32' );
// returns 'float64'

If not provided data types, the function returns a promotion table.

var out = promotionRules();
// returns {...}

var f32 = out[ 'float32' ];
// returns {...}

var rule = f32[ 'uint32' ];
// returns 'float64'

If provided an unrecognized or unsupported dtype, the function returns null.

var out = promotionRules( 'foo', 'generic' );
// returns null

Notes

• If a data type to which data types can be safely cast does not exist (or is not supported), the function returns -1.

Examples

var dtypes = require( '@stdlib/array-dtypes' );
var promotionRules = require( '@stdlib/array-promotion-rules' );

var DTYPES;
var dt1;
var dt2;
var dt;
var i;
var j;

// Get the list of supported array data types:
DTYPES = dtypes();

// Print the promotion rule for each pair of array data types...
for ( i = 0; i < DTYPES.length; i++ ) {
    dt1 = DTYPES[ i ];
    for ( j = 0; j < DTYPES.length; j++ ) {
        dt2 = DTYPES[ j ];
        dt = promotionRules( dt1, dt2 );
        console.log( '(%s, %s) => %s', dt1, dt2, dt );
    }
}

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See Also

• @stdlib/array-dtypes: list of array data types.
• @stdlib/array-safe-casts: return a list of array data types to which a provided array data type can be safely cast.
• @stdlib/ndarray-promotion-rules: return the ndarray data type with the smallest size and closest kind to which ndarray data types can be safely cast.

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.