dfloor

Round each element in a double-precision floating-point strided array toward negative infinity.

Usage

var dfloor = require( '@stdlib/math/strided/special/dfloor' );

dfloor( N, x, strideX, y, strideY )

Rounds each element in a double-precision floating-point strided array x toward negative infinity and assigns the results to elements in a double-precision floating-point strided array y.

var Float64Array = require( '@stdlib/array/float64' );

var x = new Float64Array( [ -1.1, 1.1, 3.8, 4.5, 5.9 ] );

// Perform operation in-place:
dfloor( x.length, x, 1, x, 1 );
// x => <Float64Array>[ -2.0, 1.0, 3.0, 4.0, 5.0 ]

The function accepts the following arguments:

  • N: number of indexed elements.
  • x: input Float64Array.
  • strideX: index increment for x.
  • y: output Float64Array.
  • strideY: index increment for y.

The N and stride parameters determine which elements in x and y are accessed at runtime. For example, to index every other value in x and to index the first N elements of y in reverse order,

var Float64Array = require( '@stdlib/array/float64' );

var x = new Float64Array( [ -1.1, 1.1, 3.8, 4.5, 5.9, -6.7 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dfloor( 3, x, 2, y, -1 );
// y => <Float64Array>[ 5.0, 3.0, -2.0, 0.0, 0.0, 0.0 ]

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

var Float64Array = require( '@stdlib/array/float64' );

// Initial arrays...
var x0 = new Float64Array( [ -1.1, 1.1, 3.8, 4.5, 5.9, -6.7 ] );
var y0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element

dfloor( 3, x1, -2, y1, 1 );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, -7.0, 4.0, 1.0 ]

dfloor.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )

Rounds each element in a double-precision floating-point strided array x toward negative infinity and assigns the results to elements in a double-precision floating-point strided array y using alternative indexing semantics.

var Float64Array = require( '@stdlib/array/float64' );

var x = new Float64Array( [ -1.1, 1.1, 3.8, 4.5, 5.9 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dfloor.ndarray( x.length, x, 1, 0, y, 1, 0 );
// y => <Float64Array>[ -2.0, 1.0, 3.0, 4.0, 5.0 ]

The function accepts the following additional arguments:

  • offsetX: starting index for x.
  • offsetY: starting index for y.

While typed array views mandate a view offset based on the underlying buffer, the offsetX and offsetY parameters support indexing semantics based on starting indices. For example, to index every other value in x starting from the second value and to index the last N elements in y,

var Float64Array = require( '@stdlib/array/float64' );

var x = new Float64Array( [ -1.1, 1.1, 3.8, 4.5, 5.9, -6.7 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dfloor.ndarray( 3, x, 2, 1, y, -1, y.length-1 );
// y => <Float64Array>[ 0.0, 0.0, 0.0, -7.0, 4.0, 1.0 ]

Examples

var uniform = require( '@stdlib/random/base/uniform' );
var Float64Array = require( '@stdlib/array/float64' );
var dfloor = require( '@stdlib/math/strided/special/dfloor' );

var x = new Float64Array( 10 );
var y = new Float64Array( 10 );

var i;
for ( i = 0; i < x.length; i++ ) {
    x[ i ] = uniform( -10.0, 10.0 );
}
console.log( x );
console.log( y );

dfloor.ndarray( x.length, x, 1, 0, y, -1, y.length-1 );
console.log( y );

C APIs

Usage

#include "stdlib/math/strided/special/dfloor.h"

stdlib_strided_dfloor( N, *X, strideX, *Y, strideY )

Rounds each element in a double-precision floating-point strided array X toward negative infinity and assigns the results to elements in a double-precision floating-point strided array Y.

#include <stdint.h>

const double X[] = { -1.5, 2.3, -3.9, 4.2, -5.0, -6.0, 7.9, -8.1 };
double Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

const int64_t N = 4;

stdlib_strided_dfloor( N, X, 2, Y, 2 );

The function accepts the following arguments:

  • N: [in] int64_t number of indexed elements.
  • X: [in] double* input array.
  • strideX: [in] int64_t index increment for X.
  • Y: [out] double* output array.
  • strideY: [in] int64_t index increment for Y.
void stdlib_strided_dfloor( const int64_t N, const double *X, const int64_t strideX, double *Y, const int64_t strideY );

Examples

#include "stdlib/math/strided/special/dfloor.h"
#include <stdint.h>
#include <stdio.h>

int main( void ) {
    // Create an input strided array:
    const double X[] = { -1.5, 2.3, -3.9, 4.2, -5.0, -6.0, 7.9, -8.1 };

    // Create an output strided array:
    double Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

    // Specify the number of elements:
    const int64_t N = 4;

    // Specify the stride lengths:
    const int64_t strideX = 2;
    const int64_t strideY = 2;

    // Compute the results:
    stdlib_strided_dfloor( N, X, strideX, Y, strideY );

    // Print the results:
    for ( int i = 0; i < 8; i++ ) {
        printf( "Y[ %i ] = %lf\n", i, Y[ i ] );
    }
}

See Also

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