> RT-qPCR is directly a O(2^N) signal. The signal is actually more like N*2^C where C is the number of cycles (usually around 30). So a huge amplification, but

> RT-qPCR is directly a O(2^N) signal. The signal is actually more like N*2^C where C is the number of cycles (usually around 30). So a huge amplification, but still linear in the starting amount, i.e. O(N). That's actually more useful, generally, since ratios of amplified material stay approximately constant during amplification.