For Y=f(X 1, X2, X3, ... Xn)

n

The uncertainty is u (y) = √ [√ (df/dxi) * (df/dxi) * u (I) * u (I)];

i= 1

n

The relative uncertainty is ur = √ [√ (d (INF)/dxi) * (d (INF)/dxi) * u (I) * u (I)].

i= 1

N and I are above and below ∑ respectively.