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Arithmetics and elementary functions

In this article we show how to do simple numerical operations with arrays.
© CC-BY-NC-SA 4.0 by CSC - IT Center for Science Ltd.

Element-wise operations

Simple calculations are very straightforward with NumPy arrays.

Basic arithmetic operations (+ - * / **) can all be used with arrays. The main
thing to keep in mind is that most operations are done element-wise.

a = numpy.array([1.0, 2.0, 3.0])
b = 2.0

print(a * b)
# output: [ 2. 4. 6.]

print(a + b)
# output: [ 3. 4. 5.]

print(a * a)
# output: [ 1. 4. 9.]

Elementary functions

NumPy provides also a wide range of elementary mathematical functions (sin,
cos, exp, sqrt, log, …) that work with arrays (as well as single values). In
many ways NumPy can be used as a drop-in replacement for the math module.

import numpy, math
a = numpy.linspace(-math.pi, math.pi, 8)

print(a)
# output:
# [-3.14159265 -2.24399475 -1.34639685 -0.44879895 0.44879895 1.34639685
# 2.24399475 3.14159265]

print(numpy.sin(a))
# output:
# [ -1.22464680e-16 -7.81831482e-01 -9.74927912e-01 -4.33883739e-01
# 4.33883739e-01 9.74927912e-01 7.81831482e-01 1.22464680e-16]

print(math.sin(a))
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: only length-1 arrays can be converted to Python scalars
© CC-BY-NC-SA 4.0 by CSC - IT Center for Science Ltd.
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Python in High Performance Computing

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