gonum.org/v1/gonum@v0.14.0/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  	"gonum.org/v1/gonum/internal/asm/f64"
     9  )
    10  
    11  // Ddot computes the dot product of the two vectors
    12  //
    13  //	\sum_i x[i]*y[i]
    14  func (Implementation) Ddot(n int, x []float64, incX int, y []float64, incY int) float64 {
    15  	if incX == 0 {
    16  		panic(zeroIncX)
    17  	}
    18  	if incY == 0 {
    19  		panic(zeroIncY)
    20  	}
    21  	if n <= 0 {
    22  		if n == 0 {
    23  			return 0
    24  		}
    25  		panic(nLT0)
    26  	}
    27  	if incX == 1 && incY == 1 {
    28  		if len(x) < n {
    29  			panic(shortX)
    30  		}
    31  		if len(y) < n {
    32  			panic(shortY)
    33  		}
    34  		return f64.DotUnitary(x[:n], y[:n])
    35  	}
    36  	var ix, iy int
    37  	if incX < 0 {
    38  		ix = (-n + 1) * incX
    39  	}
    40  	if incY < 0 {
    41  		iy = (-n + 1) * incY
    42  	}
    43  	if ix >= len(x) || ix+(n-1)*incX >= len(x) {
    44  		panic(shortX)
    45  	}
    46  	if iy >= len(y) || iy+(n-1)*incY >= len(y) {
    47  		panic(shortY)
    48  	}
    49  	return f64.DotInc(x, y, uintptr(n), uintptr(incX), uintptr(incY), uintptr(ix), uintptr(iy))
    50  }