github.com/gopherd/gonum@v0.0.4/blas/gonum/level1float64_ddot.go (about)

     1  // Copyright ©2015 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package gonum
     6  
     7  import (
     8  	"github.com/gopherd/gonum/internal/asm/f64"
     9  )
    10  
    11  // Ddot computes the dot product of the two vectors
    12  //  \sum_i x[i]*y[i]
    13  func (Implementation) Ddot(n int, x []float64, incX int, y []float64, incY int) float64 {
    14  	if incX == 0 {
    15  		panic(zeroIncX)
    16  	}
    17  	if incY == 0 {
    18  		panic(zeroIncY)
    19  	}
    20  	if n <= 0 {
    21  		if n == 0 {
    22  			return 0
    23  		}
    24  		panic(nLT0)
    25  	}
    26  	if incX == 1 && incY == 1 {
    27  		if len(x) < n {
    28  			panic(shortX)
    29  		}
    30  		if len(y) < n {
    31  			panic(shortY)
    32  		}
    33  		return f64.DotUnitary(x[:n], y[:n])
    34  	}
    35  	var ix, iy int
    36  	if incX < 0 {
    37  		ix = (-n + 1) * incX
    38  	}
    39  	if incY < 0 {
    40  		iy = (-n + 1) * incY
    41  	}
    42  	if ix >= len(x) || ix+(n-1)*incX >= len(x) {
    43  		panic(shortX)
    44  	}
    45  	if iy >= len(y) || iy+(n-1)*incY >= len(y) {
    46  		panic(shortY)
    47  	}
    48  	return f64.DotInc(x, y, uintptr(n), uintptr(incX), uintptr(incY), uintptr(ix), uintptr(iy))
    49  }