R nls2 "неверная модель формулы", подходящая гамма

Question

Работаем в R 3.1.3 и Rstudio.

Я хочу приспособить гамма-распределения, которые включают в себя параметр местоположения, к данным, чтобы "сдвинуть" значения x к новому источнику. Я пытаюсь использовать nls2 со следующим кодом:

library(nls2)

theVals <- data.frame(c(26.76,24.3,34.63,38.05,25.56,21.98,20.62,34,26.75,27.79,28.4,33.31,29.26,18.65,22.77,25.72,25.86,25.32,24.08,27.68,26.2,26.16,25.34,26.91,22.6,23.94,23.3,22.34,41.25,24.83,21.66,30.47,26.53,27.74,29.41,25.65,36.05,18.29,27.2,22.99,25.8,21.9,25.27,30.29,22.72,26.49,18.75,33.57,20.87,21.82,20.73,28.59,19.64,33.21,28.94,27.98,22.2,25.95,30.64,26.56,32.11,26.05,20.66,28.64,22.4,22.4,31.91,21.82,26.82,20.77,24.12,28.83,23.07,26.5,21.14,27.29,19.61,25.28,28.6,27.16,22.46,18.19,22.35,23.79,26.32,26.5,27.39,23.29,25.79,26.35,26.38,24.98,20,37.15,25.61,21.39,21.63,24.12,24.4,27.72,42.74,25.33,17.79,21.33,38.65,25.22,28.39,21.61,23.38,25.25,24.88,23.34,26.26,21.96,22.18,24.78,21.15,24.65,21.23,31.9,28.66,27.66,18.08,22.99,22.46,21.69,28.21,29.8,25.72,27.09,20.02,21.26,21.34,27.18,25.48,20.51,20.96,20.07,20.89,27.56,24.43,21.35,24.3,28.1,26.53,29.03,30.08,19.19,21.27,26.18,23.79,36.52,24.81,26.36,24.44,20.99,19.84,23.32,18.21,26.6,21.48,23.21,29.93,23.4,30.9,23.58,21.58,18.38,25.13,23.03,22.73,24.42,22.89,43.44,23.47,27.09,29.96,23.94,28.51,25.74,28.54,30.41,22.7,29.19,25.66,23.89,21.9,36.26,22.61,19.68,27.85,28.83,28.6,22.68,19.07,20.22,24.35,19.09,37.66,22.55,24.25,22.61,26.09,24.42,26.11,32.15,25.78,21.94,23.93,30.19,23.53,26.49,30.48,25.02,28.14,23.43,20.22,17.57,21.68,36.07,24.92,32.48,32.04,25.86,26.69,22.41,26.4,22.72,28.32,22.82,32.73,28.08,29.16,36.18,21.61,23.9,28.8,23.24,24.89,22.17,27.7,34.75,26.74,29.62,17.46,20.06,22.23,22.09,24.05,22.37,24.98,33.26,30.95,26.24,22.16,30.97,27.22,23.81,42.16,28.2,28.37,26.1,26.28,27.44,20.52,35.02,21.43,23.14,18.37,28.86,25.18,28.15,19.97,24.2,25.91,28.92,23.95,19.48,28.57,21.77,23.46,37.51,22.13,37.18,21.83,23.8,18.93,27.43,26.51,25.64,22.15,22.27,29.21,24.45,18.81,22.62,25.16,24.62,30.53,28.77,27.11,22.07,28.95,26.54,39.23,31.9,33,29.93,24.37,26.4,21.33,25.37,25.9,21.25,19.06,25.69,26.44,26.09,23.24,27.04,20.09,28.73,37.06,32.45,22.93,22.7,24.82,31.23,23.25,22.94,20.47,25.7,23.92,34.71,26.5,20.28,21.78,26.54,30.34,21.97,27.38,27.64,34.08,22.05,27.21,20.11,25.79,33.22,31.24,29.93,21.81,30.68,32.46,30.45,22.62,28.83,33.95,27.12,45.51,25.23,29.61,29.09))

colnames(theVals) <- c("theGamma")

fo <- theGamma ~ dgamma(theX-location, shape=theShape, scale=theScale  )
startList <- list(location=5, theShape=3, theScale=3)
theGamma=NULL
theX <- 0:50
mo1 <- nls2(fo, start=startList, data=theVals)

Я получаю сообщение об ошибке "неверная формула модели в ExtractVars".

Любопытно работает дгамма

 location<- 5
 theShape <- 3
 theScale <- 3

 dgamma(theX-location, shape=theShape, scale=theScale  )

У меня есть поиск по стеку и другие сайты, но я не могу найти ответ на этот.

Есть идеи?