Vector.go

package main

import (
	"errors"
	"fmt"
	"math"
)

type Vector struct {
	Body []float64
}


func (vector Vector) Norm() float64 {
	norm := 0.0
	for _, x := range vector.Body {
		norm += math.Pow(x, 2)
	}
	return norm
}

func (vector Vector) Size() int {
	return len(vector.Body)
}


func (vector Vector) String() string {
	return fmt.Sprintf("Vector: %v with size %v", vector.Body, vector.Size())
}

func (vector1 Vector) AddVector(vector2 Vector) (Vector, error) {
	err := check_vector_sizes_equal(vector1, vector2)
	if err != nil {
		return Vector{}, err
	}
	var new_body []float64
	for i := range vector1.Body {
		new_body = append(new_body, vector1.Body[i] + vector2.Body[i])
	}
	return Vector{new_body}, nil
}

func (vector Vector) MultiplyByInt(f float64) Vector {
	var new_body []float64
	for i := range vector.Body {
		new_body = append(new_body, vector.Body[i] * f)
	}
	return Vector{new_body}
}


func (vector1 Vector) DotProduct(vector2 Vector) (float64, error) {
	err := check_vector_sizes_equal(vector1, vector2)
	if err != nil {
		return 0, err
	}
	result := 0.0
	for i := range vector1.Body {
		result += vector1.Body[i] * vector2.Body[i]
	}
	return result, nil
}

func (vector1 Vector) CalculateAngleBetweenVectors(vector2 Vector) (float64, error) {
	dot_product, err := vector1.DotProduct(vector2)
	if err != nil {
		return 0, err
	}

	err = check_vector_norms_non_zero(vector1, vector2)
	if err != nil {
		return 0, err
	}

	return math.Acos(dot_product / (vector1.Norm() * vector2.Norm())), nil
}

func check_vector_sizes_equal(vector1 Vector, vector2 Vector) error {
	if vector1.Size() != vector2.Size() {
		error_text := fmt.Sprintf("Vectors with different sizes: %v and %v", vector1, vector2)
		return errors.New(error_text)
	}
	return nil
}

func check_vector_norms_non_zero(vectors ...Vector) error {
	for _, vector := range vectors {
		if vector.Norm() == 0 {
			error_text := fmt.Sprintf("Vector %v has zero norm", vector)
			return errors.New(error_text)
		}
	}
	return nil
}