blob: 2b44fe924dea635399ef335b974a1979d4c59c2d [file] [log] [blame]
// Copyright ©2015 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gonum
import (
"gonum.org/v1/gonum/internal/asm/f64"
)
// Ddot computes the dot product of the two vectors
// \sum_i x[i]*y[i]
func (Implementation) Ddot(n int, x []float64, incX int, y []float64, incY int) float64 {
if incX == 0 {
panic(zeroIncX)
}
if incY == 0 {
panic(zeroIncY)
}
if n <= 0 {
if n == 0 {
return 0
}
panic(negativeN)
}
if incX == 1 && incY == 1 {
if len(x) < n {
panic(badLenX)
}
if len(y) < n {
panic(badLenY)
}
return f64.DotUnitary(x[:n], y)
}
var ix, iy int
if incX < 0 {
ix = (-n + 1) * incX
}
if incY < 0 {
iy = (-n + 1) * incY
}
if ix >= len(x) || ix+(n-1)*incX >= len(x) {
panic(badLenX)
}
if iy >= len(y) || iy+(n-1)*incY >= len(y) {
panic(badLenY)
}
return f64.DotInc(x, y, uintptr(n), uintptr(incX), uintptr(incY), uintptr(ix), uintptr(iy))
}