Python | Numpy np.legvander() method (original) (raw)

Last Updated : 31 Dec, 2019

**np.legvander()** method is used to returns the Vandermonde matrix of degree deg and sample points x.

Syntax : np.legvander(x, deg)
Parameters:
**x :**[ array_like ] Array of points. The dtype is converted to float64 or complex128 depending on whether any of the elements are complex. If x is scalar it is converted to a 1-D array.
**deg :**[int] Degree of the resulting matrix.

Return : Return the matrix having size i.e array.size + (degree + 1).

Example #1 :
In this example we can see that by using np.legvander() method, we are able to get the pseudo-vandermonde matrix using this method.

import numpy as np

import numpy.polynomial.legendre as geek

ans = geek.legvander(( 1 , 3 , 5 , 7 ), 2 )

print (ans)

Output :

[[ 1. 1. 1.]
[ 1. 3. 13.]
[ 1. 5. 37.]
[ 1. 7. 73.]]

Example #2 :

import numpy as np

import numpy.polynomial.legendre as geek

ans = geek.legvander(( 1 , 2 , 3 , 4 ), 3 )

print (ans)

Output :

[[ 1. 1. 1. 1. ]
[ 1. 2. 5.5 17. ]
[ 1. 3. 13. 63. ]
[ 1. 4. 23.5 154. ]]

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