Abstract: A gas multiple component analyzer includes an infrared source that passes at least one measuring beam through a sample cell that contains the gas to be analyzed. Three measuring signals are generated in response to the measuring beam, and each is indicative of optical energy from the source transmitted through the sample cell in a respective optical region characterized by a respective optical center wave-length and a respective band pass. The three measuring signals are algebraically combined to automatically determine which of the three end gases is present in the sample cell in the greatest concentration, and the concentration thereof. The disclosed system measures concentration of three separate gases having overlapping absorption spectra.