[BioC] Fitting a contrast matrix in Limma

[Laura Hollins]

Hi,
 
I have been trying to fit a contrast matrix in Limma using the
'contrasts.fit' function but I keep getting an error:
 
Error in La.chol(crossprod(design)) : the leading minor of order 5 is
not positive definite
 
I entered my design and contrast matrices from tab-delimited files
created on Excel using the 'read.delim' function and I then had to
convert them into matrices from data frames. In the past, I have typed
smaller, less complex design and contrast matrices directly into R and
had no problems.
 
Does anyone know what this error means or how to resolve it? 
 
Thanks,
 
Laura
 
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