#2 [Enhancement] multivector multiplication for power systems

[paketecuento]

Hi, great job and nice tool!!

I'd like to know if you are able to introduce some minor tweaks for multiplying multivectors according to some spcial rules in the non-sinusoidal power field.
When we multiply multivector Voltage (V) and multivector Current (I), we get a new quantity labeled as M (Multivector apparent power), but it has a special requirement: every scalar, as a result of the square of a bivector, trivector and so on... should change its sign according to: f =(−1)k(k−1)/2,

As a result, when assessing the consumption or production of active power in an element, all the resulting scalar numbers must be multiplied by the f factor, where k is the mutivector grade. Consequently, for scalars resulting from the square of unit bivectors as in (σ_13)^2, for example, the sign changes as k = 2 .

[paketecuento]

I solved it just creating a copy of times.m and adding some code. Just replace in case -1 switch:

m.multivector{I} = -p;

by

if col == row
    m.multivector{I} = p;
else
    m.multivector{I} = -p;
end

and

m.multivector{I} = m.multivector{I} - p;

by

if col == row
    m.multivector{I} = m.multivector{I} + p;
else
    m.multivector{I} = m.multivector{I} - p;
end