npm package: @stdlib/lapack-base-dlamch
Description: Determine double-precision floating-point machine parameters.
Author: The Stdlib Authors
Latest version: 0.1.1

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# dlamch

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Determine double-precision floating-point machine parameters.

<section class="installation">

## Installation

```bash
npm install @stdlib/lapack-base-dlamch
```

</section>

<section class="usage">

## Usage

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

#### dlamch( cmach )

Determines double-precision floating-point machine parameters.

```javascript
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.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   `dlamch()` corresponds to the [LAPACK][lapack] function [`dlamch`][lapack-dlamch].

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
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 );
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
TODO
```

#### TODO

TODO.

```c
TODO
```

TODO

```c
TODO
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
TODO
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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[deno-url]: https://github.com/stdlib-js/lapack-base-dlamch/tree/deno
[deno-readme]: https://github.com/stdlib-js/lapack-base-dlamch/blob/deno/README.md
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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/lapack-base-dlamch/main/LICENSE

[lapack]: https://www.netlib.org/lapack/explore-html/

[lapack-dlamch]: https://www.netlib.org/lapack/explore-html/d4/d86/group__lamch_gaeab255e77cbd3b0f31aea74ed0ce099e.html#gaeab255e77cbd3b0f31aea74ed0ce099e

</section>

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