modcost

modcost(gencost, alpha, modtype)

modcost() - Modifies generator costs by shifting or scaling (F or X).

NEWGENCOST = MODCOST(GENCOST, ALPHA)
NEWGENCOST = MODCOST(GENCOST, ALPHA, MODTYPE)

For each generator cost F(X) (for real or reactive power) in
GENCOST, this function modifies the cost by scaling or shifting
the function by ALPHA, depending on the value of MODTYPE, and
and returns the modified GENCOST. Rows of GENCOST can be a mix
of polynomial or piecewise linear costs. ALPHA can be a scalar,
applied to each row of GENCOST, or an NG x 1 vector, where each
element is applied to the corresponding row of GENCOST.

MODTYPE takes one of the 4 possible values (let F_alpha(X) denote the
the modified function):
    'SCALE_F' (default) : F_alpha(X)         == F(X) * ALPHA
    'SCALE_X'           : F_alpha(X * ALPHA) == F(X)
    'SHIFT_F'           : F_alpha(X)         == F(X) + ALPHA
    'SHIFT_X'           : F_alpha(X + ALPHA) == F(X)