truncn

Round a numeric value to the nearest multiple of 10^n toward zero.

Usage

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

truncn( x, n )

Rounds a numeric value to the nearest multiple of 10^n toward zero.

// Round a value to 4 decimal places:
var v = truncn( 3.141592653589793, -4 );
// returns 3.1415

// If n = 0, `truncn` behaves like `trunc`:
v = truncn( 3.141592653589793, 0 );
// returns 3.0

// Round a value to the nearest thousand:
v = truncn( 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.

Examples

var randu = require( '@stdlib/random/base/randu' );
var truncn = require( '@stdlib/math/base/special/truncn' );

var x;
var n;
var v;
var i;

for ( i = 0; i < 100; i++ ) {
    x = (randu()*100.0) - 50.0;
    n = truncn( randu()*5.0, 0 );
    v = truncn( x, -n );
    console.log( 'x: %d. Number of decimals: %d. Rounded: %d.', x, n, v );
}

C APIs

Usage

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

stdlib_base_truncn( x, n )

Rounds a numeric value to the nearest multiple of 10^n toward zero.

double y = stdlib_base_truncn( 3.141592653589793, -4 );
// 3.1415

The function accepts the following arguments:

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

double stdlib_base_truncn( const double x, const int32_t n );

Examples

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

int main( void ) {
    const double x[] = { 3.141592653589793, -3.141592653589793, 2.731, 3.55555 };

    double y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_truncn( x[ i ], -2 );
        printf( "truncn(%lf) = %lf\n", x[ i ], y );
    }
}