sdot

Calculate the dot product of two single-precision floating-point vectors.

The dot product (or scalar product) is defined as

Usage

var sdot = require( '@stdlib/blas/sdot' );

sdot( x, y[, dim] )

Calculates the dot product of two single-precision floating-point vectors x and y.

var Float32Array = require( '@stdlib/array/float32' );
var array = require( '@stdlib/ndarray/array' );

var x = array( new Float32Array( [ 4.0, 2.0, -3.0, 5.0, -1.0 ] ) );
var y = array( new Float32Array( [ 2.0, 6.0, -1.0, -4.0, 8.0 ] ) );

var z = sdot( x, y );
// returns <ndarray>

var v = z.get();
// returns -5.0

The function has the following parameters:

x: a non-zero-dimensional ndarray whose underlying data type is float32. Must be broadcast-compatible with y.
y: a non-zero-dimensional ndarray whose underlying data type is float32. Must be broadcast-compatible with x.
dim: dimension for which to compute the dot product. Must be a negative integer. Negative indices are resolved relative to the last array dimension, with the last dimension corresponding to -1. Default: -1.

If provided at least one input ndarray having more than one dimension, the input ndarrays are broadcasted to a common shape. For multi-dimensional input ndarrays, the function performs batched computation, such that the function computes the dot product for each pair of vectors in x and y according to the specified dimension index.

var Float32Array = require( '@stdlib/array/float32' );
var array = require( '@stdlib/ndarray/array' );

var opts = {
    'shape': [ 2, 3 ]
};
var x = array( new Float32Array( [ 4.0, 2.0, -3.0, 5.0, -1.0, 3.0 ] ), opts );
var y = array( new Float32Array( [ 2.0, 6.0, -1.0, -4.0, 8.0, 2.0 ] ), opts );

var z = sdot( x, y );
// returns <ndarray>

var v1 = z.get( 0 );
// returns 23.0

var v2 = z.get( 1 );
// returns -22.0

Notes

The size of the contracted dimension must be the same for both input ndarrays.
The function resolves the dimension index for which to compute the dot product before broadcasting.
Negative indices are resolved relative to the last ndarray dimension, with the last dimension corresponding to -1.
The output ndarray has the same data type as the input ndarrays and has a shape which is determined by broadcasting and excludes the contracted dimension.
If provided empty vectors, the dot product is 0.
sdot() provides a higher-level interface to the BLAS level 1 function sdot.

Examples

var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var array = require( '@stdlib/ndarray/array' );
var sdot = require( '@stdlib/blas/sdot' );

var opts = {
    'dtype': 'float32'
};

var x = array( discreteUniform( 10, 0, 100, opts ), {
    'shape': [ 5, 2 ]
});
console.log( ndarray2array( x ) );

var y = array( discreteUniform( 10, 0, 10, opts ), {
    'shape': x.shape
});
console.log( ndarray2array( y ) );

var z = sdot( x, y, -1 );
console.log( ndarray2array( z ) );