xpress.Sum
xpress.Sum |
Purpose
Alternative sum operator for an arbitrary number of objects created by a list, tuple, generator, NumPy array, dictionary, etc.
Synopsis
a = xpress.Sum(t1, t2, ...)
Example
The following are allowed uses of the
Sum operator:
import math
N = 20
S = range(S)
x = [xpress.var() for i in S]
y = [xpress.var(vartype=xpress.binary) for i in S]
p = xpress.problem()
p.addVariable(x, y)
p.setObjective(x[0] + xpress.Sum(x[i]**2 for i in S))
p.addConstraint(xpress.Sum(x,y) <= 100)
p.addConstraint(xpress.Sum(x[:i]) + xpress.Sum(y[:i])
<= math.log(10 + i) for i in S)
Further information
The Sum operator is functionally equivalent to Python's native sum operator. However, it is strongly advised to use the Xpress' Sum operator when constructing large expressions involving variables, as doing otherwise might slow down the execution significantly.