A system includes a plurality of thermally-coupled zones and a plurality of thermal control devices, each controllable to thermally control one of the plurality of zones, and a plurality of temperature sensors, each configured to measure temperature of one of the plurality of zones. The system includes a control circuit configured to receive a temperature measurement for each of the plurality of zones, collect the temperature measurements in a temperature vector in a real coordinate system, and transform the temperature vector to a normal coordinate system that provides a plurality of uncoupled equations. The control circuit is configured to determine, based on the plurality of uncoupled equations and a desired temperature gradient, a desired power vector in the normal coordinate system, transform the desired power vector to the real coordinate system to generate a power vector, and control the plurality of heaters in accordance with the power vector.