conditonal "if"

I replicated your error. 

tau2ca <- NA
if (tau2ca==0) {x <- 0.01} else {x <- tau2ca}

Hope it helps. And I couldn't replicate your second program, but it seems
ok.


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Hi,

I have problem with my R program. Actually, it just a simple program, but I do
not know the error is. Here is part of my program:

....
if (tau2ca==0) {MVvc<- 0.01} else {MVvc<- tau2ca}
ri_vc<- si2/MVvc
vi_vc<- ri_vc + 1
Y_bar_vc<- sum(y/vi_vc)/sum((1/vi_vc))
tau2MVvc<- sum((1/vi_vc)*(y - Y_bar_vc)^2)/(k-1)
....

But then, there is an error displayed in workspace

Error in if (tau2ca == 0) { : missing value where TRUE/FALSE needed

I do not know why there is an error like that.

R is telling you exactly why there is an error.  The "if" statement needs to 
evaluate to TRUE or FALSE, but it is evaluating to a missing value (e.g., NA). 
tau2ca is probably NA at that point.

Since you don't provide a reproducible example as the posting guide asks, I have 
no idea why it is missing.

 > Also, I just want to make sure whether my program below is right or

not.

for (l in 1:k)
{if (a[l]==0 | b[l]==0 | c[l]==0 | d[l]==0)
{ a[l]<- a[l]+0.5
  b[l]<- b[l]+0.5
  c[1]<- c[1]+0.5
  d[1]<- d[1]+0.5
}
}

Since this is not self-contained, nor are your objectives stated, there is no 
way to tell you wheter or not the program is "correct".

There is surely a vectorized/list approach to what you want to do.