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functions: smooth_val $steps
              swap_valval2_valbakval2bak
              swap_val_val2
-------------------------------------------


Smooths gradient vectors currently residing in
the valbak/val2bak fields (vertex[i].valbak,
vertex[i].val2bak).

Here are tcl script commands used for 10 steps
(~3 mm FWHM) of surface-smoothing:

  swap_valval2_valbakval2bak 
  swap_val_val2
  smooth_val 10
  swap_val_val2
  smooth_val 10
  swap_valval2_valbakval2bak

This can be used on any complex-valued data in
valbak/val2bak.

This can also be done using the tcl wrapper
function, smooth, as follows:

  smooth <steps> <type>
  smooth 10 grad 

