> mydata<- read.csv ("D:\\MY Data\\R\\Tri-set.csv" , sep=",", dec=".", header=TRUE)
> mydata1 <- drm (Survival ~ Dose, Herbicide, fct = W1.3(), data=mydata)
> summary(mydata1)

Model fitted: Weibull (type 1) with lower limit at 0 (3 parms)

Parameter estimates:

       Estimate Std. Error t-value   p-value    
b:EC   1.440454   0.239782  6.0073 3.346e-06 ***
b:MC   1.915474   0.320034  5.9852 3.533e-06 ***
d:EC 100.489083   5.303133 18.9490 6.368e-16 ***
d:MC 100.356215   5.257064 19.0898 4.791e-16 ***
e:EC   0.711835   0.054866 12.9740 2.444e-12 ***
e:MC   0.637447   0.042248 15.0882 9.551e-14 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error:

 9.398498 (24 degrees of freedom)
> EDcomp(mydata1, c(10,10), interval = "delta")

Estimated ratios of effect doses

            Estimate   Lower   Upper
EC/MC:10/10  0.75802 0.18863 1.32740
> EDcomp(mydata1, c(50,50), interval = "delta") 

Estimated ratios of effect doses

            Estimate   Lower   Upper
EC/MC:50/50  1.04841 0.77686 1.31997
> EDcomp(mydata1, c(90,90), interval = "delta")

Estimated ratios of effect doses

            Estimate  Lower  Upper
EC/MC:90/90   1.2891 0.9224 1.6559

> relpot(mydata1, plotit = TRUE, compMatch = NULL, percVec = NULL, interval = "none", type="relative")
Error in match.fun(FUN) : 
  'object$fct$lowerAs' is not a function, character or symbol