Sorry I'm student in biomedical engineer and i have to solve this formula for immuno-assay. I need to design a calibration curve
But i don't understand How can i write this formula in R language: y = a + (c - a) /(1+ e[-b(x-m]) where x = ln(analyte dose + 1) y = the optical absorbance data a = the curves top asymptote b = the slope of the curve c = the curves bottom asymptote m = the curve X intercept I have to calculate the parameters (a,b,c,m).After with X that i know i calculate the Y. i try: yeld.fit <- nls( y ~ a + (c.-a)/(1+exp(-b*(x-m))), data = yeld, start = list( a= 0, c.=2, b= 1, m=4 ), trace = TRUE ) where yeld is a data.frame x y 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 but give me an error: << exceeded number of itwerations>> thank you Andrea ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help