Since perl doesn't implement copysign or signbit and won't let you divide by zero, the best bet is to just check for the minus: 
$sign = $B[0] =~ /^\s*-/ ? -1 : 1;
@result = map {$_*$sign} @B[1..$#B];

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In reply to Re: Applying Sign Bit by Anonymous Monk
in thread Applying Sign Bit by budman

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