modulus()

MODULUS is used to calculates the modulus of the spectrum.

In 2D, will only works for fully Hypercomplex data-sets (itype ==
3) or for data-sets complex in F2 (itype == 1) not for data-set
complex in F1 (itype == 2). In this last case, you should use FLOP
before doing MODULUS.

see also : flip flop real abs

NPK Documentation, version 0.995 - 2009-10-14