I have two TF1 functions f1 and f2. f1 is used to fit some data set and f2 is used to fit some other data set. Now I have a 3rd function f3 which is the multiplication of f1 and f2. The parameters and errors in parameter of f3 are those obtained from fitting of two data sets by f1 and f2. Now I am trying to calculate IntegralError in the function f3 for which I have to supply the covariance matrix. Since f1 and f2 are used in fitting I can calculate their covariance matrix but how to find covariance matrix of the third function f3 which is just the multiplication of two functions f1 and f2 ?
Please help me in solving the above problem.___
ROOT Version: 6.16
Platform: Mac OS
Compiler: Not Provided