Displaying 1 result from an estimated 1 matches for "psi_f".
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psi_c
2011 Oct 11
1
singular gradient error in nls
...ime*60 #convert to seconds
b2 <- 1-(0.196/(0.06/0.01131)) #relationship between soil moisture and the
size of the ring infiltrometer (6 cm radius by 113.1 cm2 cross sectional
area)
theta <- 0.196 #difference in residual soil water and field capacity
Here is the formula:
#Where a = K_fs and b=psi_f
nlsfit <-
nls(time.s~(theta/a*b2)*((cumul.m/theta)-(((0.16-b)/b2)*log(1+((cumul.m*b2)/(theta*(0.16-b)))))),
data = df, start=list (a=1, b=0.5), trace=TRUE)
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I am likely "over parameterizing", but I must admit, that I am not entirely
sure what that means. Any help offered would b...