[BioC] BioC 1.4 MAS implementation

[Lizhe Xu]

Please help me with the MAS method. 
I got more than half of the probe sets with value as NA (16645 for U133A) after using the following command:

> set<-expresso(data, normalize.method="constant", bgcorrect.method="mas", pmcorrect.method="subtractmm",summary.method="mas")
background correction: mas 
normalization: constant 
PM/MM correction : subtractmm 
expression values: mas 
background correcting...done.
normalizing...done.
22283 ids to be processed
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|####################|
There were 50 or more warnings (use warnings() to see the first 50)

When I checked the warnings it showed
> warnings()
Warning messages:
1: NaNs produced in: log(x, base) 
2: NaNs produced in: log(x, base) 
3: NaNs produced in: log(x, base) 
4: NaNs produced in: log(x, base) 
5: NaNs produced in: log(x, base) 
6: NaNs produced in: log(x, base) 
7: NaNs produced in: log(x, base) 
8: NaNs produced in: log(x, base) 
9: NaNs produced in: log(x, base) 
10: NaNs produced in: log(x, base) 

Did I make some mistake on the command? What do the warnings mean?

Thanks.


L