NONLINEAR DATA FITTING FOR CONTROLLED-RELEASE DEVICES - AN INTEGRATEDCOMPUTER-PROGRAM

A computer program, MSFIT, was developed for nonlinear fitting of rele ase data from controlled release devices. The program is written in th e C language, based on the high level user-interface Macintosh operati ng system. Five popular release models are implemented in the program. Initial estimates of the parameters are obtained by linear transforma tion followed by linear fitting of the fraction released-time data. No nlinear model fitting is based on the maximum likelihood estimation me thod and is performed by the Levenberg-Marquardt method based on the c hi(2) criterion. Several methods are available to aid the evaluation o f the fitting results. The MSFIT program was used for the nonlinear fi tting of several release data sets and results were satisfactory.