Hi I am not sure if my interpretation of the following derivative is correct. N = I / R - D Where , N, I and D are integers, while R is a fraction (1% to 15%). If I differentiate the above equation with respect to R, I get the following equation. dN/dR = I / R^2 The following is my interpretation of this derivative. 1. The lower the value of R, the higher the value of dN/dR, at a given I 2. At a given R, the higher the value of I , the higher the value of dN/dR 3. If I plot dN/dR against R, at various values of I, I will get exponentially declining curves, with curves with higher I values lying on the left of curves with lower I values. Thank you, MG.