ramp
Evaluate the ramp function for each element in a strided array.
The ramp function is defined as
or, alternatively, in terms of the max function
Usage
var ramp = require( '@stdlib/math/strided/special/ramp' );
ramp( N, dtypeX, x, strideX, dtypeY, y, strideY )
Evaluates the ramp function for each element in a strided array x and assigns the results to elements in a strided array y.
var Float64Array = require( '@stdlib/array/float64' );
var x = new Float64Array( [ 1.1, 2.5, -3.5, 4.0, -5.9 ] );
// Perform operation in-place:
ramp( x.length, 'float64', x, 1, 'float64', x, 1 );
// x => <Float64Array>[ 1.1, 2.5, 0.0, 4.0, 0.0 ]
The function accepts the following arguments:
- N: number of indexed elements.
- dtypeX: data type for
x. - x: input array-like object.
- strideX: index increment for
x. - dtypeY: data type for
y. - y: output array-like object.
- 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 the first N elements of y in reverse order,
var Float64Array = require( '@stdlib/array/float64' );
var x = new Float64Array( [ 1.1, 2.5, -3.5, 4.0, -5.9, 6.4 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
ramp( 3, 'float64', x, 2, 'float64', y, -1 );
// y => <Float64Array>[ 0.0, 0.0, 1.1, 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, 2.5, -3.5, 4.0, -5.9, 6.4 ] );
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
ramp( 3, 'float64', x1, -2, 'float64', y1, 1 );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, 6.4, 4.0, 2.5 ]
ramp.ndarray( N, dtypeX, x, strideX, offsetX, dtypeY, y, strideY, offsetY )
Evaluates the ramp function for each element in a strided array x and assigns the results to elements in a strided array y using alternative indexing semantics.
var Float64Array = require( '@stdlib/array/float64' );
var x = new Float64Array( [ 1.1, 2.5, -3.5, 4.0, -5.9 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
ramp.ndarray( x.length, 'float64', x, 1, 0, 'float64', y, 1, 0 );
// y => <Float64Array>[ 1.1, 2.5, 0.0, 4.0, 0.0 ]
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, 2.5, -3.5, 4.0, -5.9, 6.4 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
ramp.ndarray( 3, 'float64', x, 2, 1, 'float64', y, -1, y.length-1 );
// y => <Float64Array>[ 0.0, 0.0, 0.0, 6.4, 4.0, 2.5 ]
Examples
var uniform = require( '@stdlib/random/base/uniform' ).factory;
var filledarray = require( '@stdlib/array/filled' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var dtypes = require( '@stdlib/array/typed-real-float-dtypes' );
var ramp = require( '@stdlib/math/strided/special/ramp' );
var dt;
var x;
var y;
var i;
dt = dtypes();
for ( i = 0; i < dt.length; i++ ) {
x = filledarrayBy( 10, dt[ i ], uniform( -10.0, 10.0 ) );
console.log( x );
y = filledarray( 0.0, x.length, 'generic' );
console.log( y );
ramp.ndarray( x.length, dt[ i ], x, 1, 0, 'generic', y, -1, y.length-1 );
console.log( y );
console.log( '' );
}