Concerning the dissolution of drug (%dissolved) with respect t time (x)The equation I have for cumulative Weibull equation with slope and intercept from a book is as follows:

y=a+b(1-exp(-((x+dln(2)1/e-c)/d)e)) ......b is intercept on y axis and e is intecept on x axis (time).

y is % drug dissolved.

I am usign a nonlinear regreession program to solve the equation for a data set, but it will not accept the equation as shown. Can the expressson be written in a more articulate way. Are we short of parenthesis to provide correct structure? I am sure the program will accept the equation, but I must enter it more articulately to get the program to read the equation properly.

Please can suggetions be made how to write above equation such that it will run on program.

Angus