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I would like to code the following in R: a1(b1+b2+b3) + a2(b1+b3+b4) + a3(b1+b2+b4) + a4(b1+b2+b3) or in summation notation: sum_{i=1, j\neq i}^{4} a_i * b_i I realise this is the same as: sum_{i=1, j=1}^{4} a_i * b_i - sum_{i=j} a_i * b_i would appreciate some help. Thank you. -- View this message in context: http://r.789695.n4.nabble.com/summation-coding-tp4646678.html Sent from the R

I am trying to use the optim command to get the MLEs for a number of parameters based on some data. Is it possible to write a program that maximizes the likelihood and stores the parameters (many times)? I need to do this a lot of times, each time the data will be updated with more entries (rows). I need to see how the new data is affecting the previous parameter estimates of the model. What is

Hi, I have a data frame and I need to add another column. I am using: data[,4] <- ifelse(data[,3]<1,data[,1]/(1-data[,3]),"NA") This is returning values but are in quotation marks. The error I am getting is "non-numeric argument to binary operator" I need column four in data to be numeric. Tried as.numeric but it did not work well either. Would appreciate any help.