Hi all I need to calculate the area under a curve (integral) for the following data pairs:
Depth SOC 22.5 0.143 28.5 0.165 34.5 0.131 37.5 0.134 40.5 0.138 43.5 0.107 46.5 0.132 49.5 0.175 52.5 0.087 55.5 0.117 58.5 0.126 61.5 0.13 64.5 0.122 67.5 0.161 71.5 0.144 76.5 0.146 82.5 0.156 94.5 0.132 (Table name is P) After reading the data set I assiged the collumns by: /x <- (P$Depth) y <- (P$SOC) / and decided to make a ploynominal function (3rd order): /fitP <- lm( y~poly(x,3,raw=TRUE) )/ At the next step I failed. I can plot point and function but am not able to integrate the curve between e.g. depths 20 and 80. If I try: / integrand <-function(fitP1) predict(y) integrate(integrand, lower = 25, upper = 80)/ the "Conosle" opend with the message: "Source unavailable or out of sync" and / function(fitP1) predict(y) / ) Would be great if somebody could help! Thanks Carsten -- View this message in context: http://r.789695.n4.nabble.com/Calculate-the-area-under-a-curve-tp4711418.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
