numpy.expm1() in Python

Last Updated : 29 Nov, 2018

numpy.expm1(array, out = None, where = True, casting = 'same_kind', order = 'K', dtype = None) : This mathematical function helps user to calculate exponential of all the elements subtracting 1 from all the input array elements. Parameters :

  array    : [array_like]Input array or object whose elements, we need to test.  out      : [ndarray, optional]Output array with same dimensions as Input array,              placed with result.  **kwargs : allows you to pass keyword variable length of argument to a function.              It is used when we want to handle named argument in a function.  where    : [array_like, optional]True value means to calculate the universal              functions(ufunc) at that position, False value means to leave the              value in the output alone.

Return :

  An array with exponential(all elements of input array) - 1.

Code 1 : Working

Python

# Python program explaining # expm1() function  import numpy as np  in_array = [1, 3, 5] print ("Input array : \n", in_array)  exp_values = np.exp(in_array) print ("\nExponential value of array element : "        "\n", exp_values)  expm1_values = np.expm1(in_array) print ("\n(Exponential value of array element) - (1) "        ": \n", expm1_values)

Output :

  Input array :    [1, 3, 5]    Exponential value of array element :    [   2.71828183   20.08553692  148.4131591 ]    (Exponential value of array element) - (1) :    [   1.71828183   19.08553692  147.4131591 ]

Code 2 : Graphical representation

Python

# Python program showing # Graphical representation of  # expm1() function  import numpy as np import matplotlib.pyplot as plt  in_array = [1, 1.2, 1.4, 1.6, 1.8, 2] out_array = np.expm1(in_array)  print("out_array : ", out_array)  y = [1, 1.2, 1.4, 1.6, 1.8, 2] plt.plot(in_array, y, color = 'blue', marker = "*")  # red for numpy.expm1() plt.plot(out_array, y, color = 'red', marker = "o") plt.title("numpy.expm1()") plt.xlabel("X") plt.ylabel("Y") plt.show()