truncb
Round a numeric value to the nearest multiple of b^n toward zero.
Usage
var truncb = require( '@stdlib/math/base/special/truncb' );
truncb( x, n, b )
Rounds a numeric
value to the nearest multiple of b^n
toward zero.
// Round a value to 4 decimal places:
var v = truncb( 3.141592653589793, -4, 10 );
// returns 3.1415
// If n = 0 or b = 1, `truncb` behaves like `trunc`:
v = truncb( 3.141592653589793, 0, 2 );
// returns 3.0
// Round a value to the nearest multiple of two toward zero:
v = truncb( 5.0, 1, 2 );
// returns 4.0
Notes
- Due to rounding error in floating-point numbers, rounding may not be exact.
Examples
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var pow = require( '@stdlib/math/base/special/pow' );
var truncb = require( '@stdlib/math/base/special/truncb' );
var x;
var n;
var b;
var v;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*100.0) - 50.0;
n = round( (randu()*10.0) - 5.0 );
b = round( randu()*10.0 );
v = truncb( x, n, b );
console.log( 'x: %d. %d^%d: %d. Rounded: %d.', x, b, n, pow( b, n ), v );
}
C APIs
Usage
#include "stdlib/math/base/special/truncb.h"
stdlib_base_truncb( x, n, b )
Rounds a numeric
value to the nearest multiple of b^n
toward zero.
double out = stdlib_base_truncb( 3.141592653589793, -4, 10 );
// returns 3.1415
The function accepts the following arguments:
- x:
[in] double
input value. - n:
[in] int32_t
power. - b:
[in] int32_t
base.
double stdlib_base_truncb( const double x, const int32_t n, const int32_t b );
Examples
#include "stdlib/math/base/special/truncb.h"
#include <stdio.h>
#include <stdint.h>
int main( void ) {
const double x[] = { -5.0, -3.89, -2.78, -1.67, -0.56, 0.56, 1.67, 2.78, 3.89, 5.0 };
const int32_t n[] = { -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 };
const int32_t b[] = { 20, 19, 18, 17, 16, 15, 14, 13, 12, 11 };
double v;
int i;
for ( i = 0; i < 10; i++ ) {
v = stdlib_base_truncb( x[ i ], n[ i ], b[ i ] );
printf( "truncb(%lf, %d, %d) = %lf\n", x[ i ], n[ i ], b[ i ], v );
}
}