Round a double-precision floating-point number to the nearest value with N significant figures.
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> Round a double-precision floating-point number to the nearest value with n significant figures.
``bash`
npm install @stdlib/math-base-special-roundsd
`javascript`
var roundsd = require( '@stdlib/math-base-special-roundsd' );
#### roundsd( x, n\[, b] )
Rounds a double-precision floating-point number to the nearest value with n significant figures.
`javascript
var v = roundsd( 3.141592653589793, 3 );
// returns 3.14
v = roundsd( 3.141592653589793, 1 );
// returns 3.0
v = roundsd( 12368.0, 2 );
// returns 12000.0
`
The default base is 10 (decimal). To round using a different base, provide a third argument.
`javascript`
var v = roundsd( 0.0313, 2, 2 );
// returns 0.03125
`javascript
var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var roundsd = require( '@stdlib/math-base-special-roundsd' );
var opts = {
'dtype': 'float64'
};
var x = uniform( 100, -5000.0, 5000.0, opts );
logEachMap( 'x: %0.4f. y: %d. Rounded: %0.4f.', x, 5, roundsd );
`
*
`c`
#include "stdlib/math/base/special/roundsd.h"
#### stdlib_base_roundsd( x, n, b )
Rounds a double-precision floating-point number to the nearest value with n significant figures.
`c`
double v = stdlib_base_roundsd( 3.141592653589793, 3, 10 );
// returns 3.14
The function accepts the following arguments:
- x: [in] double input value.[in] int32_t
- n: number of significant figures.[in] int32_t
- b: base.
`c`
double stdlib_base_roundsd( const double x, const int32_t n, const int32_t b );
`c
#include "stdlib/math/base/special/roundsd.h"
#include
int main( void ) {
const double x[] = { 3.143546, -3.142635, 0.0, 0.0/0.0 };
double y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_roundsd( x[ i ], 2, 10 );
printf( "roundsd(%lf) = %lf\n", x[ i ], y );
}
}
`
*
- [@stdlib/math-base/special/ceilsd][@stdlib/math/base/special/ceilsd]: round a numeric value to the nearest number toward positive infinity with N significant figures.
- [@stdlib/math-base/special/floorsd][@stdlib/math/base/special/floorsd]: round a numeric value to the nearest number toward negative infinity with N significant figures.
- [@stdlib/math-base/special/round][@stdlib/math/base/special/round]: round a numeric value to the nearest integer.
- [@stdlib/math-base/special/truncsd][@stdlib/math/base/special/truncsd]: round a numeric value to the nearest number toward zero with N significant figures.
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/math-base-special-roundsd/tree/deno
[deno-readme]: https://github.com/stdlib-js/math-base-special-roundsd/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/math-base-special-roundsd/tree/umd
[umd-readme]: https://github.com/stdlib-js/math-base-special-roundsd/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/math-base-special-roundsd/tree/esm
[esm-readme]: https://github.com/stdlib-js/math-base-special-roundsd/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/math-base-special-roundsd/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-base-special-roundsd/main/LICENSE
[@stdlib/math/base/special/ceilsd]: https://www.npmjs.com/package/@stdlib/math-base-special-ceilsd
[@stdlib/math/base/special/floorsd]: https://www.npmjs.com/package/@stdlib/math-base-special-floorsd
[@stdlib/math/base/special/round]: https://www.npmjs.com/package/@stdlib/math-base-special-round
[@stdlib/math/base/special/truncsd]: https://www.npmjs.com/package/@stdlib/math-base-special-truncsd