Hi,

limma function fitFDist() has a bug, triggered under rare circumstances.  As per the documentation:

fitFDist(x, df1, covariate=NULL)

where

df1: the first degrees of freedom of the F-distribution. Can be a single value, or else a vector of the same length as x.

In the case when df1 is a single value and one or more of the x values is not finite or below hard-coded limits, the function fails with:

Error in if (evar > 0) { : missing value where TRUE/FALSE needed

The reason is in this piece of fitFDist() code, at about line 22:

    ok <- is.finite(x) & is.finite(df1) & (x > -1e-15) & (df1 > 1e-15)
    notallok <- !all(ok)
    if (notallok) {
        x <- x[ok]
        df1 <- df1[ok]
        if (!is.null(covariate)) {
            covariate2 <- covariate[!ok]
            covariate <- covariate[ok]
        }
    }

The highlighted line will produce a list of NAs, which later on produces the error in line 74. A simple way to reproduce the error is to run the example in the vignette of package betr.

By the way, the length of df1 is not checked before use, and could fail in other places.

Line numbers are from stripped code.  Using:

R version 3.3.2 (2016-10-31)
Platform: x86_64-redhat-linux-gnu (64-bit)
Running under: Fedora 25 (Workstation Edition)

[1] limma_3.30.7     betr_1.33.0

Thanks !

--c

Thanks for spotting this. An even simpler failing example would just be:

fitFDist(c(NA, 1), 1)

... which yields the same error as your original post. Funnily enough, we had spotted and fixed the same bug last year in the fitFDistRobustly function; I guess we never got around to fixing it for fitFDist itself.