Works for me: 
perl -E '@dipept = qw/XX AA BB CC DDAAD AAAAAAA/; $FMat[0][0] = grep(/
+AA/, @dipept); say $FMat[0][0]'
3

[download]
The documentation of grep clearly states:
In scalar context, returns the number of times the expression was true.
What input do you have? What output do you expect?
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: Using grep in a scalar context by choroba
in thread Using grep in a scalar context by newbie1991

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