vectors.py

# Vectors in Python without numpy
# juhani Kaukoranta
# 11.2.2019

from math import sqrt, acos, degrees
from operator import mul

def dotproduct(a,b):
    return sum(map(mul,a,b))
def norm(a):
    # norm, length of vector a
    return sqrt(dotproduct(a,a))

def anglerad(a,b):
    # angle between vectors a and b in radians
    return acos(dotproduct(a,b)/norm(a)/norm(b))

def angledeg(a,b):
    # angle between vectors a and b in radians
    return degrees(anglerad(a,b))

def crossproduct(a,b):
    assert len(a) == len(b) == 3, 'Only 3D vectors, set missing component to 0'
    a1,a2,a3 = a
    b1,b2,b3 = b
    return [a2*b3 - a3*b2, a3*b1 - a1*b3, a1*b2 - a2*b1]

print("for example input vector  [-3,5,4] are inputed : -3 5 4")
# vector1
input_vector = input("Enter first vector's components separated by space ")
# muutetaan listan merkkijonokomponentit liukuluvuiksi
vector1 = [float(i) for i in input_vector.split()]
print("vector1 = ",vector1)
# vector2
input_vector = input("Enter second vector's components separated by space ")
vector2 = [float(i) for i in input_vector.split()]
print("vector2 = ",vector2)
# dot product, norm, angle, cross product
print("dotproduct of vectors = ",dotproduct(vector1,vector2))
print("norm, length of vector1 = ",norm(vector1))
print("norm, length of vector2 = ",norm(vector2))
print("angle between vectors in radians = ",anglerad(vector1,vector2))
print("angle between vectors in degrees = ",angledeg(vector1,vector2))
print("cross product of vectors = ",crossproduct(vector1,vector2))