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makoru-hikage/summation_notation.py

Last active October 12, 2017 11:47
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A simple implementation of summation notation in Python
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summation_notation.py
"""
## Derived from here:
## https://math.stackexchange.com/questions/1694311/is-sigma-sigma-a-mathematical-way-of-doing-a-for-loop/1694322
## (c) CC-BY-SA 3.0
"""
## Definition
def sum_notation(i=0, end=1, f= lambda x : x):
return f(i) + sum_notation(i+1, end, f) if (i <= end) else 0
## Usage
y = lambda x : 1 / (2 ** x)
print (sum_notation(0, 3))
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If you use capital Sigma or capital Pi notation, use tail call recursion instead.

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