roundsd

Round a double-precision floating-point number to the nearest value with n significant figures.

Installation

npm install @stdlib/math-base-special-roundsd

Usage

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.

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.

var v = roundsd( 0.0313, 2, 2 );
// returns 0.03125

Examples

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 APIs

Usage

#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.

double v = stdlib_base_roundsd( 3.141592653589793, 3, 10 );
// returns 3.14

The function accepts the following arguments:

• x: [in] double input value.
• n: [in] int32_t number of significant figures.
• b: [in] int32_t base.

double stdlib_base_roundsd( const double x, const int32_t n, const int32_t b );

Examples

#include "stdlib/math/base/special/roundsd.h"
#include <stdio.h>

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 );
    }
}

See Also

• @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: round a numeric value to the nearest number toward negative infinity with N significant figures.
• @stdlib/math-base/special/round: round a numeric value to the nearest integer.
• @stdlib/math-base/special/truncsd: round a numeric value to the nearest number toward zero with N significant figures.

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

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.