# Python | Numpy np.lagder() method

• Last Updated : 29 Dec, 2019

`np.lagroots()` method is used to differentiate a Laguerre series.

Syntax : `np.lagder(c, m=1, scl=1, axis=0)`
Parameters:
c :[array_like] 1-D arrays of Laguerre series coefficients ordered from low to high.
m :[int, optional] Number of derivatives taken, must be non-negative.Default is 1.
scl :[scalar, optional] Each differentiation is multiplied by scl .Default is 1.
axis :[ int, optional] Axis over which the derivative is taken.Default is 0.

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Return : [ndarray] Laguerre series of the derivative.

Code #1 :

 `# Python program explaining``# numpy.lagder() method ``   ` `# importing numpy as np  ``# and numpy.polynomial.laguerre module as geek ``import` `numpy as np ``import` `numpy.polynomial.laguerre as geek``   ` `# Input laguerre series coefficients`` ` `s ``=` `(``2``, ``4``, ``8``) ``    ` `# using np.lagder() method ``res ``=` `geek.lagder(s) `` ` `# Resulting laguerre series coefficient``print` `(res) `
Output:
```[-12.  -8.]
```

Code #2 :

 `# Python program explaining``# numpy.lagder() method ``   ` `# importing numpy as np  ``# and numpy.polynomial.laguerre module as geek ``import` `numpy as np ``import` `numpy.polynomial.laguerre as geek``   ` `# Laguerre series coefficients``s ``=` `(``1``, ``2``, ``3``, ``4``, ``5``) `` ` `   ` `# using np.lagder() method ``res ``=` `geek.lagder(s, m ``=` `2``, scl ``=` `0.5``) `` ` `# Resulting laguerre series``print` `(res) `
Output:
```[ 6.5   3.5   1.25]

```

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