// Copyright 2019 The Go 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 linalg import "math" // Numeric is type bound that matches any numeric type. // It would likely be in a constraints package in the standard library. type Numeric interface { type int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64, complex64, complex128 } func DotProduct[T Numeric](s1, s2 []T) T { if len(s1) != len(s2) { panic("DotProduct: slices of unequal length") } var r T for i := range s1 { r += s1[i] * s2[i] } return r } // NumericAbs matches numeric types with an Abs method. type NumericAbs[T any] interface { Numeric Abs() T } // AbsDifference computes the absolute value of the difference of // a and b, where the absolute value is determined by the Abs method. func AbsDifference[T NumericAbs](a, b T) T { d := a - b return d.Abs() } // OrderedNumeric is a type bound that matches numeric types that support the < operator. type OrderedNumeric interface { type int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64 } // Complex is a type bound that matches the two complex types, which do not have a < operator. type Complex interface { type complex64, complex128 } // OrderedAbs is a helper type that defines an Abs method for // ordered numeric types. type OrderedAbs[T OrderedNumeric] T func (a OrderedAbs[T]) Abs() OrderedAbs[T] { if a < 0 { return -a } return a } // ComplexAbs is a helper type that defines an Abs method for // complex types. type ComplexAbs[T Complex] T func (a ComplexAbs[T]) Abs() ComplexAbs[T] { r := float64(real(a)) i := float64(imag(a)) d := math.Sqrt(r * r + i * i) return ComplexAbs[T](complex(d, 0)) } func OrderedAbsDifference[T OrderedNumeric](a, b T) T { return T(AbsDifference(OrderedAbs[T](a), OrderedAbs[T](b))) } func ComplexAbsDifference[T Complex](a, b T) T { return T(AbsDifference(ComplexAbs[T](a), ComplexAbs[T](b))) }