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dlamch

Determine double-precision floating-point machine parameters.

Installation

npm install @stdlib/lapack-base-dlamch

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 dlamch = require( '@stdlib/lapack-base-dlamch' );

dlamch( cmach )

Determines double-precision floating-point machine parameters.

var out = dlamch( 'E' );
// returns 1.1102230246251565e-16

The function has the following parameters:

• cmach: specifies the value to be returned. The following characters are supported:

  • 'E'/'e': (eps) relative machine precision.
  • 'S'/'s': (sfmin) safe minimum such that 1/sfmin does not overflow.
  • 'B'/'b': (base) base of the machine (also known as the floating-point radix).
  • 'P'/'p': (prec) eps*base.
  • 'N'/'n': (t) number of (base) digits in the mantissa.
  • 'R'/'r': (rnd) 1.0 when rounding occurs in addition and 0.0 otherwise.
  • 'M'/'m': (emin) minimum exponent before (gradual) underflow.
  • 'U'/'u': (rmin) underflow threshold.
  • 'L'/'l': (emax) largest exponent before overflow.
  • 'O'/'o': (rmax) overflow threshold.

Notes

• dlamch() corresponds to the LAPACK function dlamch.

Examples

var dlamch = require( '@stdlib/lapack-base-dlamch' );

var out = dlamch( 'E' );
console.log( 'Precision: %d', out );

out = dlamch( 'S' );
console.log( 'Safe minimum: %d', out );

out = dlamch( 'B' );
console.log( 'Base: %d', out );

out = dlamch( 'P' );
console.log( 'Precision*base: %d', out );

out = dlamch( 'N' );
console.log( 'Number of digits in mantissa: %d', out );

out = dlamch( 'R' );
console.log( 'Rounding: %d', out );

out = dlamch( 'M' );
console.log( 'Minimum exponent before underflow: %d', out );

out = dlamch( 'U' );
console.log( 'Underflow threshold: %d', out );

out = dlamch( 'L' );
console.log( 'Maximum exponent before overflow: %d', out );

out = dlamch( 'O' );
console.log( 'Overflow threshold: %d', out );

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C APIs

Usage

TODO

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TODO

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Examples

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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 © 2016-2025. The Stdlib Authors.