As the questions states, lets consider we have 3 gas sensors giving me data for:
Note that only sensors for A and B give absolute values, yet we need the absolute values for all four species:
Where the sum of the four gases are 1: A + B + C + D = 100%.
Where should I start solving this problem from? How can the general case be described mathematically?
EDIT: As a real-world example, lets consider that:
GSensorA: O2 Sensor
GSensorB: CO2 Sensor
GSensorC: Pollution Sensor
GSensorD: Nitrogen via Signal Processing ;)
My objective is to obtain fairly accurate air composition, based on the assumption that the air around us is composed only of oxygen, nitrogen, carbon dioxide and pollutants respectively. Therefore, if we know the volume composition of 3 of the above species, we will have the forth: which is where the title of this question comes from.
By absolute, I am referring to the fact that it is zero-referenced and is independent or other values. I'm sorry if this caused confusion.