The steps taken to fix an R problem.

Task

To prepare for the Portfolio Probe blog post called “Implied alpha and minimum variance”, I tried to update a matrix of daily stock prices using a function I had written for the purpose.

Error

When I tried to do what I wanted, I got:

> univclose130518 <- pp.updateclose(jjuc[,1:5])
done with: MMM  ABT  ANF  ACE  ACN  
Error in if (beg > end) stop("Start date must be before end date.") : 
  missing value where TRUE/FALSE needed

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