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PhDP/linear-upper.py

Created April 11, 2012 11:39
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Convert a linear index to X-Y coordinates from an upper triangular matrix
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linear-upper.py
def getX(i):
return int(-0.5 + 0.5 * sqrt(1 + 8 * (i - 1))) + 2
def getY(i):
return getX(i) * (3 - getX(i)) / 2 + i - 1
def getXY(i):
return (getX(i + 1) - 1, getY(i + 1) - 1)
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