Abstract: Provided herein are molecular analog gene circuits that exploit positive and negative feedback to implement logarithmically linear sensing, addition, subtraction, and scaling thus enabling multiplicative, ratiometric, and power-law computations. The circuits exhibit Weber's Law behavior as in natural biological systems, operate over a wide dynamic range of up to four orders of magnitude, and can be architected to have tunable transfer functions. The molecular circuits described herein can be composed together to implement higher-order functions that are well-described by both intricate biochemical models and by simple mathematical functions. The molecular circuits described herein enable logarithmically linear analog computation within in-vitro and in-vivo systems with a broad class of molecules, all of which obey the Boltzmann exponential equations of thermodynamics that govern molecular association, attenuation, transformation, and degradation.