Hi, we have a function that calculates a value for each day of the year. For example an iterative function like actvalue_0 := 0 actvalue_ {t+1} := actvalue_t + f(param_1,param_2,actvalue_t) and for some days we have measurements. Now we want to choose param_1 and param_2 so that the function values are close to our measured values. Does anyone know how to solve this problem? Thanks, Christof