dot

VarDictND.dot(paramdict)

Sum the products of variables with corresponding coef from ParamDictND, in an expression.

Assumes the coef to be zero if not found in the ParamDictND.

Equivalent to:

xp.Sum(paramdict.get(k, 0) * v for k, v in vardict.items())

Parameters:

paramdictParamDictND

ParamDictND to be used for dot product; should have tuple keys of same length as VarDictND.

Returns:

xp.expression

Raises:

TypeError

If the paramdict is not as instance of ParamDictND.

ValueError

If the paramdict does not have tuple keys of same length as VarDictND.

Notes

This method is equivalent to using the matrix multiplication operator @.

Both ParamDictND @ VarDictND and VarDictND @ ParamDictND will also produce the same result.

Examples

Create xpress problem:

>>> import xpress as xp
>>> import warnings
>>> warnings.filterwarnings('ignore', category=xp.LicenseWarning)

>>> prob = xp.problem()

Create index-set:

>>> arcs = IndexSetND([('A', 'B'), ('B', 'C'), ('C', 'B')], names=['ori', 'des'])

Add variables:

>>> from opti_extensions.xpress import addVariables
>>> arc_flow = addVariables(prob, arcs, name='arc-flow', ub=10, vartype=xp.continuous)

Define parameter:

>>> from opti_extensions import ParamDictND
>>> cost = ParamDictND({('A', 'B'): 10, ('B', 'C'): 20})

Compute dot product (three alternative ways):

>>> arc_flow.dot(cost)
10 * arc-flow(('A', 'B')) + 20 * arc-flow(('B', 'C'))

>>> cost @ arc_flow
10 * arc-flow(('A', 'B')) + 20 * arc-flow(('B', 'C'))

>>> arc_flow @ cost
10 * arc-flow(('A', 'B')) + 20 * arc-flow(('B', 'C'))