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LAST UPDATED: JANUARY 15, 2021

# NumPy eye() function

In this tutorial, we will cover `numpy.matlib.eye()` function of the Numpy library.

The `numpy.matlib.eye()` function is used to return a matrix with all the diagonal elements initialized to 1 and with zero value elsewhere.

The `numpy.matlib` is a matrix library used to configure matrices instead of ndarray objects.

### Syntax of `matlib.eye()`:

The required syntax to use this function is as follows:

``numpy.matlib.eye(n, m, k, dtype,order)   ``

Parameters:

Let us now cover the parameters used with this function:

• n
This parameter is used to represent the number of rows in the resulting matrix.

• m
This parameter is used to represent the number of columns and the default value is `n`.

• k
This parameter is used to indicate an index of diagonal,value of this parameter is 0 by default if value of k>0 it means diagonal is above the main diagonal or vice versa.

• dtype
This parameter is used to indicate the data type of the matrix. The default value of this parameter is `float`. This is an optional parameter.

• order
This is an optional parameter that is used to indicate the insertion order of the matrix. It mainly indicates whether to store the result in C- or Fortran-contiguous order, The default value is 'C'.

Returned Values:

This method will return a n x M matrix where all elements are equal to zero, except for the kth diagonal, whose values are equal to one.

## Example 1:

Given below is a basic example for the understanding of this function:

``````import numpy as np
import numpy.matlib

x = numpy.matlib.eye(n = 4, M = 3, k = 0, dtype = int)
print("The Output is :")
print(x)``````

The Output is :
[[1 0 0]
[0 1 0]
[0 0 1]
[0 0 0]]

## Example 2:

Let's take another example, to create a matrix of different dimensions.

``````import numpy as np
import numpy.matlib

x = numpy.matlib.eye(n = 5, M = 4, k = 1, dtype = int)
print("The Output is :")
print(x)``````

The Output of the above code:

## Difference between `eye()` and `identity()`:

There is a difference between the Numpy identity() function and `eye()` function and that is, the identity function returns a square matrix having ones on the main diagonal like this:

while the `eye()` function returns a matrix having 1 on the diagonal and 0 elsewhere with respect to the value of K parameter, if value of K > 0 then it implies the diagonal above main diagonal and vice-versa.

## Summary

In this tutorial we learned about `numpy.eye()` mathematical function of the Numpy library. We also covered its syntax, parameters as well as the value returned by this function along with a few examples.

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