python find the angle between two vectors
import numpy as np x=([3,5]) y=([4,2]) # Two vectors Lx=((x)) Ly=((y)) # Equivalent to the Pythagorean theorem, find the length of the diagonal line cos_angle=(y)/(Lx*Ly) # Find the value of cos_sita and reverse the calculation, multiplying the absolute length by the cos angle for the vector length, middle school knowledge. print(cos_angle) angle=(cos_angle) angle2=angle*360/2/ # Turns into an angle print(angle2) #(y) = y=∑(ai*bi)
Algorithm for matrix multiplication
>> a=[1,2,3;4,5,6;7,8,9];
>> b=[6,6,6;6,6,6;6,6,6];
>> dot(a,
ans =
72 90 108
1*6+4*6+7*6=72
# Three add up
#dot is matrix multiplication
#print((x,x))
#34
# a=(x-y)
# print(a)
costheta=(y)/((x)*(y))
# Paradigm
# #[-1 3]
# a=(x-y)
# #[1,9]
# print((a))
# #10
# print((10))Methods for finding point product, vector length, and vector angle
The methods for finding the dot product are
- 1. (a*b)
- 2. (a*b).sum()
- 3. (a, b)
- 4. (b)
- 5. (a)
The methods for finding the length of a vector are
- 1. ((a*a).sum())
- 2. (a)
Find the angle between two vectors
By the definition of dot product, cosangle = (b)/((a) * (b))
In [25]: a = ([1,2])
In [26]: b = ([2, 1])
In [27]: dot = 0
In [28]: for e, f in zip(a, b):
...: dot += e*f
...:
In [29]: dot
Out[29]: 4
In [30]: a*b
Out[30]: array([2, 2])
In [31]: (a*b)
Out[31]: 4
In [32]: (a*b).sum()
Out[32]: 4
In [33]: (a,b)
Out[33]: 4
In [34]: (b)
Out[34]: 4
In [35]: (a)
Out[35]: 4
In [36]: amag = ((a*a).sum())
In [37]: amag
Out[37]: 2.23606797749979
In [38]: amag = (a)
In [39]: amag
Out[39]: 2.23606797749979
In [40]: cosangle = (b)/((a) * (b))
In [41]: cosangle
Out[41]: 0.7999999999999998
In [42]: angle = (cosangle)
In [43]: angle
Out[43]: 0.6435011087932847summarize
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