

This versatile equation has many uses.
Fitting data to a power series model can be difficult. The initial values generated automatically by Prism are not very helpful (all four parameters are set to 1.0). you will probably need to enter better initial values in order to fit this equation to data. The initial values of B and D are important, because small changes in those values can make a huge change in Y.
The equation is not defined, and leads to a floating point error, if X equals zero and B or D are negative numbers or if X is negative and B or D are between 0.0 and 1.0.