README.md

roundnf

Round a single-precision floating-point number to the nearest multiple of 10^n.

Usage

var roundnf = require( '@stdlib/math/base/special/roundnf' );

roundnf( x, n )

Rounds a single-precision floating-point number to the nearest multiple of 10^n.

// Round a value to 2 decimal places:
var v = roundnf( 3.1415927410125732, -2 );
// returns ~3.14

// If n = 0, `roundnf` behaves like `roundf`:
v = roundnf( 3.1415927410125732, 0 );
// returns 3.0

// Round a value to the nearest thousand:
v = roundnf( 12368.0, 3 );
// returns ~12000.0

Notes

• When operating on floating-point numbers in bases other than 2, rounding to specified digits can be inexact. For example,

  var x = 0.2 + 0.1;
  // returns 0.30000000000000004
  
  // Should round to 0.3...
  var v = roundnf( x, -16 );
  // returns 0.30000001192092896

• Ties are rounded toward positive infinity.

Examples

var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var uniform = require( '@stdlib/random/array/uniform' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var roundnf = require( '@stdlib/math/base/special/roundnf' );

var x = uniform( 100, -50.0, 50.0, {
    'dtype': 'float32'
});

var n = discreteUniform( 100, -5, 0, {
    'dtype': 'int32'
});

logEachMap( 'x: %0.8f. Number of decimals: %d. Rounded: %0.8f', x, n, roundnf );

---

C APIs

Usage

#include "stdlib/math/base/special/roundnf.h"

stdlib_base_roundnf( x, n )

Rounds a single-precision floating-point number to the nearest multiple of 10^n.

// Round a value to 2 decimal places:
float y = stdlib_base_roundnf( 3.14159f, -2 );
// returns ~3.14f

// If n = 0, `roundnf` behaves like `roundf`:
y = stdlib_base_roundnf( 3.14159f, 0 );
// returns 3.0f

The function accepts the following arguments:

• x: [in] float input value.
• n: [in] int32_t integer power of 10.

float stdlib_base_roundnf( const float x, const int32_t n );

Examples

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

int main( void ) {
    const float x[] = { 3.14f, -3.14f, 0.0f, 0.0f/0.0f };

    float y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_roundnf( x[ i ], -2 );
        printf( "roundnf(%f, -2) = %f\n", x[ i ], y );
    }
}