numpy.log1p() in Python Last Updated : 29 Nov, 2018 Comments Improve Suggest changes Like Article Like Report numpy.log1p(arr, out = None, *, where = True, casting = 'same_kind', order = 'K', dtype = None, ufunc 'log1p') : This mathematical function helps user to calculate natural logarithmic value of x+1 where x belongs to all the input array elements. log1p is reverse of exp(x) - 1. Parameters : array : [array_like]Input array or object. 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 natural logarithmic value of x + 1; where x belongs to all elements of input array. Code 1 : Working Python # Python program explaining # log1p() function import numpy as np in_array = [1, 3, 5] print ("Input array : ", in_array) out_array = np.log1p(in_array) print ("Output array : ", out_array) Output : Input array : [1, 3, 5] Output array : [ 0.69314718 1.38629436 1.79175947] Code 2 : Graphical representation Python # Python program showing # Graphical representation of # log1p() 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.log1p(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.log1xp() plt.plot(out_array, y, color = 'red', marker = "o") plt.title("numpy.log1p()") plt.xlabel("X") plt.ylabel("Y") plt.show() Output : out_array : [ 0.69314718 0.78845736 0.87546874 0.95551145 1.02961942 1.09861229] References : https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.exp.html . Comment More infoAdvertise with us Next Article numpy.log1p() in Python mohit gupta_omg :) Follow Improve Article Tags : Python Python-numpy Python numpy-Mathematical Function Practice Tags : python Similar Reads numpy.log() in Python The numpy.log() is a mathematical function that helps user to calculate Natural logarithm of x where x belongs to all the input array elements. Natural logarithm log is the inverse of the exp(), so that log(exp(x)) = x. The natural logarithm is log in base e. Syntax :numpy.log(x[, out] = ufunc 'log1 4 min read numpy.log10() in Python About : numpy.log10(arr, out = None, *, where = True, casting = 'same_kind', order = 'K', dtype = None, ufunc 'log10') : This mathematical function helps user to calculate Base-10 logarithm of x where x belongs to all the input array elements. 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