TF = truncf(F) truncates the vector/scalar field(s) F to the largest
TF = truncf(F, CUT), in addition to the truncation to the largest
centered square, also eliminates bands of width CUT along the borders of
the field (CUT is 0 by default). This is useful when boundary effects
are expected (e.g., using bwfilterf). By default, CUT is specified in
mesh units, unless the option 'phys' is specified (e.g.,
truncf(F, CUT, 'phys')).
TF = truncf(F, 'nonzero') truncates the vector/scalar field(s) F to the
smallest rectangular area excluding zero (erroneous or masked)
elements. This may be useful after using rotatef.
If no output argument, the result is displayed by showf.