Perl 如何在RRD图形参数的参数中添加公式？

这个数据是以兆瓦（毫瓦）为单位的，我想把它转换成分贝毫瓦（dBm），为此我加了一个0.01的乘数。但它不能转换dBm中的值。我该怎么做？我可以在这里添加任何公式吗？

使用子程序并将数据传递给它

E.g. I have following code,

our $timeseries = {
   _type      => 'array',
   _pdpstep   => 300,    # Time resolution
   _heartbeat => 700,    # Time of loss before going to Unknown
   _storage   => 'day',
   _ylabel    => "dBm",
   _mandatory => 'yes',

   # hwEntityOpticalRxPower dBm * 100
   ahwEORxPowre    => { label      => 'Rx Power',
                        type       => 'GAUGE',
                        probe      => '1.2.3.4.5.6.7.8',
                        min        => -3999,
                        multiplier => 0.01,
                      },

   # hwEntityOpticalTxPower dBm * 100
   bhwEOTxPower    => { label      => 'Tx Power',
                        type       => 'GAUGE',
                        probe      => '1.2.3.4.5.6.7.8',
                        # -4000 means no signal
                        min        => -3999,
                        multiplier => 0.01,
                      },

};

然后在其他地方定义子例程

data => calc(0.01),

sub calc
{
    my $var = shift;
    return $var+100;
}