# How to calculate the scalar product in Python

To calculate the scalar product between two vectors in the Python language use the dot() function in the NumPy module.

**numpy.dot(v1,v2)**

The arguments v1 and v2 are two vectors (array).

The function returns the dot product v1·v2.

**What is the dot product?** The inner product is a zero number when the two vectors are orthogonal. Two vectors are orthogonal when they form a 90 ° angle.

## Example

Import the numpy library.

import numpy as np

Define two vectors (array).

a = np.array([1,2,3], float)

b = np.array([4,5,6], float)

Use the **dot()** function to calculate the dot product.

np.dot(a,b)

The result is the dot product a·b

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It is a non-zero number. Therefore the vectors are not orthogonal to each other.

**Example 2**

Define two vectors orthogonal to each other

a = np.array([2,0], float)

b = np.array([0,4], float)

Calculate the dot product

np.dot(a,b)

In this case the scalar product a · b is zero because the two vectors are orthogonal, that is, they form an angle of 90 °.

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