[R] Trap an error from a function

[John Sorkin]

Window 7
R 2.15
 
I am writing a simulation which generates sample sized estimates from simulated data. When I run the function shown below,
power.t.test(delta=14.02528,sd=1.945226,power=0.8,sig.level=0.05)
 
I get an error message:
 
> power.t.test(delta=14.02528,sd=1.945226,power=0.8,sig.level=0.05)
Error in uniroot(function(n) eval(p.body) - power, c(2, 1e+07)) : 
  f() values at end points not of opposite sign
 
The fact that the function can not return a sample size is OK, however I need to trap the error and set the sample size equal to NA. How do I trap the error so that when the error occurs I can set sample size equal to NA? 
 
Thanks,
John
 
 
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
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