[PD] absolute values of a list of numbers?

[Peter P.]

Hi list,

I am using William Brent's [cepstrum~] to calculate cepstral
coefficients from a section of an audio signal. My object outputs 512
the real-valued coefficients as pd message list, which I would like to
convert to their absolute value. I can't seem to find an easy way to do
this except for possibly sending the list to an array and using tabread
to serialize, calculate the absolute value for every element and send it
back to another array, then requesting it as a list again. Has anyone
got a better idea? 

thank you!
P