SciPy

numpy.log10

numpy.log10(x[, out]) = <ufunc 'log10'>

Return the base 10 logarithm of the input array, element-wise.

Parameters :

x : array_like

Input values.

Returns :

y : ndarray

The logarithm to the base 10 of x, element-wise. NaNs are returned where x is negative.

See also

emath.log10

Notes

Logarithm is a multivalued function: for each x there is an infinite number of z such that 10**z = x. The convention is to return the z whose imaginary part lies in [-pi, pi].

For real-valued input data types, log10 always returns real output. For each value that cannot be expressed as a real number or infinity, it yields nan and sets the invalid floating point error flag.

For complex-valued input, log10 is a complex analytical function that has a branch cut [-inf, 0] and is continuous from above on it. log10 handles the floating-point negative zero as an infinitesimal negative number, conforming to the C99 standard.

References

[R46]M. Abramowitz and I.A. Stegun, “Handbook of Mathematical Functions”, 10th printing, 1964, pp. 67. http://www.math.sfu.ca/~cbm/aands/
[R47]Wikipedia, “Logarithm”. http://en.wikipedia.org/wiki/Logarithm

Examples

>>> np.log10([1e-15, -3.])
array([-15.,  NaN])

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