Arithmetic:

ADDITION:

[(Sa + Da),(Sc + Dc)]

SUBTRACT:

[(Sa - Da),(Sc - Dc)]

MULTIPLY:

[Sa + Da - Sa×Da, Sc×(1 - Da) + Dc×(1 - Sa) + Sc×Dc]

DIVIDE:

[Sa + Da - Sa×Da, Sc×(1 - Da) + Dc×(1 - Sa) + Sc/Dc]

REPLACE:

[Sa, Sc] (fade = 1)