Abstract: A method and an apparatus for operating directly with the program code of a process for determining the gradients of process variables of interest with respect to process parameters. Each process will contain one or more process variable declarations wherein each process variable declaration defines a process variable. There will also be one or more process function assignments associated with each process variable, wherein each process function assignment assigns a value to the associated process variable. One or more gradient variables will be introduced into the process for each process variable of interest, wherein each gradient variable corresponds to and represents the partial derivative, or gradient, of the process variable of interest with respect to a parameter whose value affects the value of the process variable of interest.