$fraction = '-32 2/5';
&fconv(\$fraction);

sub fconv {
    my $f = shift;
    if ($$f =~ /(-?) ?((\d+) )?(\d+) ?\/ ?(\d+)/) {
        $$f = ($1 eq '-' ? -1 : 1) * ($3 + $4/$5);
    }
}