Variables

from gana import Prg, I, V

p = Prg()

Index Sets

Variables can (ideally should) be declared at some index

p.y = I(size=2, tag='year')
p.q = I(size=4, tag='quarter')
p.p = I('pv', 'wf', tag='variable renewable energy processes')

Non-negative Variables

These are continuous variable sets with a lower bound of 0. In my experience, most variables are of this type which is why these are the default variable type!

p.cap = V(p.p, p.y, tag='Nameplate Capacity')
p.prod = V(p.p, p.y, p.q, tag='Process Utilized in time (t)')
p.prod.show()

\[\displaystyle {prod}_{p, y, q}\]

All variables inside the set can also be displayed.

p.cap.show(True)

\[\displaystyle {{cap}}_{pv, y{0}}\]

\[\displaystyle {{cap}}_{pv, y{1}}\]

\[\displaystyle {{cap}}_{wf, y{0}}\]

\[\displaystyle {{cap}}_{wf, y{1}}\]

Integer Variables

These are non-negative discrete variables. Integer variables with an upper bound of zero are binary

p.x = V(p.p, p.y, bnr=True, tag='binary variable, 1 if process is set up')
p.n = V(p.p, p.y, itg=True, tag='integer variable, number of processes set up')

Free Variables

p.rev = V(
    p.p,
    p.y,
    p.q,
    nn=False,
    tag='unbounded variable, revenue can be positive or negative',
)

Note

gana, at the moment, is not particularly adept at handling non-linear (\(x^{i}: i > 1\)) or free variables. It will be, give me time.